just to keep it simple, you have 259 pounds to allow for the 5th wheel hitch, clothes, and bedding. A half ton truck is simply not strong enough to pull a 5th wheel with any kind of safety. I have seen many 3/4 ton trucks pulling 5th wheels and their nose is in the air because they are over loaded. with a trailer the size you are talking an 3/4 ton is necessary. Your only alternative is to get a regular travel trailer and use an equalizer hitch that will force the weight to be distributed over the entire vehicle or bite the bullet and get a 3/4 ton truck in addition to the 5er.