When buying a used camper, the better camper is usually the better camper. As in: is it well kept, does it have any pre-existing damage/repairs, does everything work as it should.
Climb inside and try to picture how you would spend a chilly, rainy day inside the camper.
The market for good used campers is pretty small. Production figures are not huge to begin with. Be prepared to look at a number of different offerings, drive a good distance in the process, and buy what suits you best. The really good offerings are usually not on the market for very long, unfortunately.
The weight aspect, with a trailer, has been discussed to death and you are aware of that.
I wish you luck and Happy Camping!