We are running a 1999 National Tradewinds 36 FT. with one slide and 90000 miles on it. Bought it in 03 and have driven it from east coast to west coast, from Florida to Texas to New York. Have replaced tires twice , fuel filters, repaired coach heater fan motor, had dash air worked on, replaced front air bags, and maintained as needed. No big problems, but the Generac generator has been the biggest PITB as I have had it worked on 4 different times.
We like it even though we only use it part time and usually take one to two long trips each year. If we could sell our house, we would go full time in it without hesitation.
As has been mentioned here on the forum, we feel that floor plan is very important along with general condition of the MH. There are many older units available that are suitable for your purpose. Good luck on your search.