Not a bad idea. In the past, ST has handled young cadets poorly, as in Wesley's character in TNG. I think the times they best portrayed cadets or young officers was with, ironically, Nog, the first Ferengi in Starfleet. Talk about a massive change, from scrounging thief to groundbreaking cadet to field promoted ensign, and eventually, to lieutenant, j.g.
Also, the TNG eps Lower Decks and The First Duty are the other best uses of young cadets/young officers. Red Squad was intriguing, but they kind of messed them up on that DSN ep that was half Lord of the Flies
and half Mutiny on the Bounty
I like your imperfectly genetically engineered character best. And hey, first Cardassian in Starfleet opens up all kinds of possibilities, esp. if set right after the war with the Dominion. I'm sure there are some cadets who had family who died in the war and might not warmly receive a Cardassian. It would be cool if the character was yet another bastard child of Gul Dukat's, as he seemed to be leaving his seed everywhere he went in the Alpha Quadrant!