If you like the motor home, go for it. You will find that there are ALWAYS going to be things wrong with it that need your attention.
IMO, you should negotiate very aggressively with current owner and discount the price (from wholesale book value) accordingly unless the owner is willing to fix the issues to your satisfaction. I see your situation as an opportunity rather than a problem. (as long as the RV is what you want and you are willing to deal with it) If not, move on.
Unless its been at the bottom of a lake or burnt to the ground, pretty much anything can be fixed. Just don't pay too much.
Chum lee