If you give us an idea of your requirements (beyond 4 beds) and the tow rating of your Xterra, it would narrow things down a bit. Budget? Bathroom?
On the small end many 13'ers have four beds and a small galley. We camp with four people (kids 10 and 13) in a basic Scamp
13'er. A step up is a Scamp
16' front bunk/side bath model. Casita
16' and 17' Spirit models can be ordered with bunks to make 4 beds. Escape
also has several models that accommodate 4 people, and they're a bit roomier than the classic rounded eggs.
Molded fiberglass options are generally not as spacious as similarly-priced conventional trailers, but they make up for it in other ways: light weight
, aerodynamic profile, low maintenance, durability, and resale value.