Generator placement

I don't think I've ever seen a gas C with the generator mounted above the floor line. That would effectively put it inside the house, even if boxed off. It is a strange checklist item for a C, but might apply to other RV types.

I've seen big diesel generators located center-forward above the chassis rails in rear-engine diesels, some Sprinter Cs supposedly have engine compartment generators, and fivers sometimes have generators in the compartments under the bedroom. Conceivably you could put one in the "garage" area of a toy hauler if that did not double as living space.

They get put where there is space to put them isolated from the living area. The above frame mounting location in the case of large diesel pushers is because those generators are big and heavy.

I wish mine was higher. It gets a beating with road dirt, and one time, I was at a CG that flooded and my generator tail pipe was submerged. Another 2 inches and all of my lower compartments would have been flooded.

Only thing I can think of is ground clearence, but there are things hanging below the generator level,ie; dump tube outlets, exhaust pipe, steps, I can't speak for a class A, but i've never seen one in a class C that was mounted any higher than lower body level.
Where did you find this "check list", not sure i'd use it, there are far more important factors in RV selection.