Lots of motorhomes have their generator mounted in the guts of the vehicle and have it on slides to get at it for servicing so I guess something could be arranged for servicing. I can get at the dipstick and water filler in the airstream onan but anything else requires it to be dropped. The small onans don't have a dipstick so oil level could be checked from underneath with a bit of modification.
The tyre on top of the camper would be more problematic. Not light to get up there and nowhere to put it if you do. Hatches and solar panels take up all the roof space on the bigfoot and I can't even stick the second unmounted spare tyre up there. It sits in the crewcab.
I know someone who made up a winch to get a large spare on top of his motorhome. Had a flat and decided to short-cut the process by throwing the spare off the roof. Didn't land as flat as he intended and bounced over the guard rail never to be seen again.
"and a diesel generator can run hundreds of hours on the top 3/4 of a tank (proper installation would have the genset cut off at the 1/4 mark for safety reasons.)"
Hard to believe I know, but several times I have been tearing my hair out trying to get the generator to start only to eventually wake up that the main fuel tank was only 1/4 full. Doh!!!
