Drew, you're right, it's all in the Details. I added a big heavy BFA genset to a coach that didn't have one before. Compartment had a floor in it and BFA was designed to use a floor. I had two helpers and we slid the 250-pound machine in from the side. Other than to get the generator lined up on the opening, a jack was no help.
Our present 4KY sets in a frame, and the access door is a hole in the side wall. This means ours would have to have the frame dismantled, then genset lowered, and height of genset + jack would require raising the coach.
I've seen some setups where there was no wall below the access door and genset was hung from its top/sides. That one would be easy...