I think you are looking at the bumper pull rating, ball on the bumper, which is 500lbs. If you have a Class III or IV hitch, the frame mounted hitch, then trailer tongue weight of the travel trailer you buy, goes against the payload of your truck.
Depending on your truck setup, crew cab, quad cab, regular cab, 5'07" bed, or 6'04" bed, motor, your payload will be different.
Your payload rating for your truck is on the sticker in the driver's side door jamb with the tire psi ratings.
Best you can do right now, is find your payload rating and then your max tow rating for your specific truck.
Once you find your payload rating, lets say it is 1430lb. payload. An 800lb. hitch weight would leave you 630lbs., for passengers and what ever cargo. You maybe right at the limit of your tow rating and your cargo capacities, depending on your travel trailer specs.