We use our camper probably more than 240 (nights) a year, either traveling or at home in the drive way. Our previous camper was sold at 8 years, was still in good shape, except for fading paint on aluminum sides. With a little TLC they can last for a long time.
My parents bought a 1963 Phoenix Travel Trailer (new) in 1962. My mother sold it in 1982 (believe it or not, still had the original tires). Mom and Dad divorced in 1970, dad had it a couple years living in it somewhere in Ohio for a couple years after that. Eventually, the camper came back to home, dad disappeared completely for a while, and Mom wanted to get rid of it. She sold it, everything still 100% functional and no leaks. However, the toilet had been removed. I think it was removed somewhere in the 10th year.
I guarantee you, neither my mother, nor my dad did any preventative maintenance on that camper. It did have an aluminum roof, and I do remember Dad taring it with black roofing tar, like on a house. That was long before they split up.
I'm not sure what happened to it with the new owners. They were family friends (their daughter wanted it), and eventually we lost all touch with them. I sure would like to have that camper back though.
So you know, they can last a long, long time if they are taken care of. It's all a matter of how much effort you want to put into it.
(See my profile ... link on the left ... for a photo of their camper).