Robert Comsol wrote:
400 aliens (i.e. not Klingons) that did serve as "slaves" to run the ship in the engineering hull.
Even before you mentioned triremes (monotremes?), I was thinking of rowers in the engineering hull. Talk about back-breaking work getting a mass that large up to the speed of light!
Then there's the A4/V2 of World War II, which killed more people from its manufacture than from its deployment.
That's not exactly what I tried to imply but for a second I was having such an image in my mind, too: "Warp Speed - Row faster you miserable dogs!"
And just as your example shows, I think it's a realistic assumption that a totalitarian state, regardless whether you think of Nazi Germany, Stalin's Russia or another totalitarian state (Klingon Empire, Romulan Star Empire, the Cardassians etc.) will abuse all the people it imprisoned and condamn these to slave labor (for whatever ethnical and/or political reasons).
DS9's mirror universe provided an illustration (although I find mining work aboard
DS9 to be rather hard to believe) but given the biohazards you'll most likely encounter in any TOS engineering hull, even the Klingons would probably put personnel there (aliens, convicts etc.) they consider to be expendable.
I'm not saying a D-7's engineering hull is a radioactive contamination hell, but probably a place where longer / permanent exposure to the radiation there will probably shorten your life expectancy considerably.