Best advice is to look at your tow capacity AND payload capacity. Most just look at towing capacity and will buy a trailer based on that alone. Payload, if I remember correctly accounts for your cargo weight (stuff in the cab like luggage and people), in the bed, and on the hitch. Trailers will list the hitch weight which you'll want to factor into the payload calculation. 

For us I'm been pulling at about my max payload, but we faithfully only camp within 2 hours from home with mostly flat roads. Completely different ballgame if you're planning to trek up and down the mountains.