How difficult is it to add a second generator?

Looking at a 54c that has a 21.5kw generator. I'd like to add a second generator (same size or slightly smaller) since we spend a lot of time on the hook, the room is there. Can anyone comment on how difficult this is in terms of labor? I've seen this done on other boats where they cut into the salon floor, which I definitely do not want to do. But it's hard for me to imagine how else to do it with a generator that size and the space to maneuver in the engine room. Any feedback appreciated.

I d be surprised if hatteras didnt built in hatches in the saloon floor.

I've not added a second generator, but I've rebuilt or replaced the 8KW genset in my 41DCMY a few times over the years. When I replaced the original Onan with a Westerbeke I bought a runout unit cheap, rebuilt it and test ran it, then disassembled it so I could carry the heaviest parts (cylinder block and generator stator) through the cabin hatch and into the engine room, then reassembled the unit. It's not as hard or time consuming as it sounds and the additional cost is a second overhaul gasket set. If you hire a mechanic to do this you'll have the additional labor to disassemble and reassemble the unit, but the labor to disassemble, bag and label parts, and reassemble the unit is much less that the labor to overhaul the unit.

If you have enough help, you might be able to carry the short block (cylinder block with the crank/cam/rods/pistons installed) into the engine room, then install the head, manifolds, and generator stator/rotor.