Where do they install a built-in generator on a fifth wheel... Seems like to me it has to be in a special location that is sealed from the living areas and have access to the ground from the bottom etc... This is in additional to providing external exhaust and electrical wiring and controls...
You are already short on storage space as it is...
I suspect the Motorhomes are designed already to have an on-board generator and the trailer type units will have to give-up some precious room to install one.
Then after you get one installed you will have to follow all the rules when you can run your generator at public places... Sure sounds like a WIN-WIN senerial to me haha...
Roy Ken