The bed platform lifts up on my Sahara allowing access to just about everything. I can also get to the entire driver's side of the engine from the area behind the generator bay. The chassis shop at the RV store I work at has 4 electric wheel lifts that can raise the coach a couple of feet to allow the tech to get under for lubing and oil changes. Cummins and Detroits with the side radiators allow access to almost the entire engine from the back doors.
I think it's harder to get at some of the gasser engines for service than it is a diesel pusher. Member fulltiming did a complete rebuild of an old gasser in
this thread. I think he did pull the engine somewhere in the 400 pages of pictures and text.