Devil Eyes, i generally agree with your overall interpretation of Dukat as being driven by a deep, twisted narcissism, vanity and sense of entitlement rather a pure, one-dimensional "eeevil" upon which one could superimpose any type of behavior.
But guess what: that same sense of delusional self-adoration, need for affirmation and sense entitlemnt - itself a noted kind of psychosis, though within Cardassia, perhaps, a respectable one - can lead people to unspeakable, thuggishly brutal acts such as rape and other kinds of sexual exploitation.
I know that a lot of time we as viewers, and Trek itself, uses Nazism as its reference point for its narratives of occupation, oppression, genocide, inhuman political actions, etc. But i'd like to reference something closer to home and the American experience than the German Nazism: American chattel slavery and post-emancipation defacto segregation.
I'd imagine you are aware that many, many slaveholders sired children through their female slaves. That women and girls were routinely raped and/or made proto "comfort women". That many were forced to raise or serve as nursemaids for the illegitimate children of slaveholders. This stuff was pretty much par for the course, and contrary, to the often reflexive anthropology employed among many liberal/rationalist types, these violators of women's bodies were not simply uneducated hicks and rednecks who were merely acting by impulse and a kind of wild-eyed non-thinking racism, but often wealthy, and well-heeled persons who were acting within accepted social mores of their particular society - even the mores accepted within "polite society" (one manifestation of this was that teenage sons of slaveholders were expected to "sow their wild oats" with slave girls and eventually, create offspring with them, although of course those offspring could never be treated like full children). Slavery was above else, a system of economic exploitation, one that mde many of its participants very, very wealthy.
And the various rationales to the ongoing sexual exploitation of black females: not only that they were the property of their owners, yes, but also that by doing this, they were actually doing the slaves a kind of existential favor, since their were children would now have the "privilege" of having white blood, lighter skin, more caucasian hair and facial features, etc. In fact, just the fact that a white man touched the slaves and took sexual interest in them was supposed to be an unmitigated good, since of course white blood was inherently superior to that of blacks. Remember that during that time, there was a entire social, political, and historical paradigm that deemed blacks as not only subhuman, but also incapable of building and/or maintaining any kind of civilization or lasting achievements. Africans were deemed to have the an intellectual, social and moral capacity as just about that of apes. Thus, slave women - as well as the men who watched as their wives and daughters were brutalized, kidnapped and made, umm, comfort women - were deemed as fortunate to have to have their captors take interest in them, and "purify" their "inferior" blood.
Of course, whenever these kinds of behaviors are deeply integrated into any kind of cultural landscape, those who have been victimized by that system can also become victimizers, and kind of perversely take on the logic of their oppressors, yet another variation of "Stockholm Syndrome". Thus, there became a fair number of black slaveholders, who were sometimes known to engage in the same practices as their white progenitors in that system. A good narrative telling of this phenomenon is in the novel and film "The Color Purple". In that fim (and obviously, the novel) the character played by Danny Glover ("Mister"), is pretty much, in most ways, a beast, though even HE is given some grey, some color to his character (and has what is in my opinion one of the most sublime and moving redemption for the character towards the end). Note that he treats the Whoopi Goldberg character ("Celie") in a perfunctory manner, there for his own use (though at times, the film shows that there can be a strange emotional connection and even functional alliance between the two); he verbally abuses and degrades the Oprah Winfrey character ("Sophia"), he flatters and lies to the Margaret Avery character ("Shug Avery") - and oh, he RAPES the Akosua Busia character ("Nettie", the younger sister of Celie). He also sires two of her children, and then sends her away. All the while, he's acting in ways that could be accepted in polite society, and in ways that were inherited tradition/ritual in the South during that time. Cardassia, anyone?
I've also known someone like this in my own family - my grandfather. He was born and reared in the South - and most definitely inherited many of the worst inclinations of his society. He was a philanderer: as with many women from her generation, black and white, my grandmother was forced to tolerate his various extramarital "affairs" and wanderings. He was something of a pedophile - targeting pubescent girls as soon as they started umm, "blooming". He could be verbally cruel - he would target enemies and opposers, perceived and otherwise, with a high degree of vitriol and viciuousness, so as to reduce them to tears.
And oh yes, he was a rapist - though not of the "hide-in-the-bushes-and-wait-to-the woman-is-home-alone" sort. No, he was what was known as an acquaintance rapist, often using charm and charisma and emotional manipulation to cause his prey to be trusting, or at least feel "safe" with him before he performed his despicable acts. Dukat, anyone?
Yet, according to many who knew him (including one of his past "conquests") he was also given to exceptional charisma, wit and often, an uncanny ability to navigate and make the most of various social, political and military circles (among, other things he was a decorated WWII vet). He was fairly well-spoken, and, even within the racist circles he often encountered, was often able to obtain positions of influence and acclaim within his community and some social organizations. Heck, he was even given to organizing all kinds of "good works" for the communities in which he lived, organizing block parties and gift giveaways to the various children within the community, who would then, along with their grateful families of course, shower him with adoration and affirmation. Sound like anyone?
Know what else? Both my mother and her sister have said that he NEVER touched them sexually and was, in many ways, a loving, protective father, though his actions against their mother and others (he could have a vicious temper) certainly created a lot of emotional instability which even today has had residual effects. And my mom told me that she knew that he would go postal if anyone had ever laid a hand a hand on her or my aunt - and in fact once almost killed a man who attempted to do just that. And despite their despising of the things he had done, my mom and her sister (along with my three uncles) most certainly loved their father. He was, after all, their father.
Ziyal, anyone?
So you see in my relative, in the "Mister" character and even the slaveholders (most of whom confessed Christianity, a faith which most definitely did NOT advocate or promote cruelty and sexual exploitation of slaves, contrary to some very uninformed opinions around these parts), a range of behaviors, characteristics, value systems and justifications driving their actions, both good and evil. But this ability to demonstrate "grey" behaviors clearly did not preclude them from the enforcement oof their greater power over vulnerable through violent sexual means - otherwise known as rape.
I think one mistake you're making in your assessment is in assuming that any suggestion that Dukat could be a rapist is a simplistic, lack-of-grey analysis, when in fact, the fictional and real-life examples that I gave demonstrate that an ability to engage in demonstrably evil behaviors does not preclude "non-evil" behaviors, such as generosity, kindness, and paternal love (of course, one of Dukat's most defining characteristics was that even his good behaviors were calibrated to be for his benefit and self-celebration)
I also thinking you may be assuming that we're assuming scenarios of Dukat as a common thug, the kind who makes the front page of the daily paper, when in fact we're all aware of his Machiavellian, function-at-the-upper-echelons-of-Cardassia and the AQ characterization. Of course, the Kennedys are/were arguably the first family of American politics, and have had tremendous influence in the worlds of law, government, economics, and social organizations (The Peace Corps, Job Corps, The Special Olympics, etc) - but they've also had within their ranks quite a few philanderers, drunks, scoundrels, and, according to some, thieves, "negligent manslaughterers", and rapists. So bad, even inhumane behavior don't have to be common thuggery to truly be criminal.
So yes, Dukat COULD clearly be a rapist.
There is absolutely no way that Dukat would ever have raped anyone.
How's life in the Fire Caves, and will we see you again soon? 
