Welcome to your new home. These forums will give you a wealth of info. We too own a 31' Sovereign
rear bath. Ours is a 67. We also have heard of the problems with the rear bath. Our attitude is that if it is something to want to own and if you get a good buy on it, all things can be fixed. We were novices (and still are) when we found ours and realize now that we paid too much for the shape it was in. However, yours sounds well worth the price, especially if all the plumbing, heating and appliances work. If you have checked it our thoroughly and love it, go for it. We love ours, even though we found that it had no furnace when we got it home, also no front couch, and no refrigerator. But, hey, "Moby" is ours and he can be fixed.
Good Luck and continue to ask questions.
Beth and/or David
67 Sovereign, double bed, rear bath-"Moby"
2005 Dodge Ram 2500 Hemi, Quad Cab-"Ahab"
"Vintage trailer, vintage owners"