This question has been asked and answered MANY times on the forum. Do some searching. There's been lots of good advice given out there - including step-by-step procedures for determining the remaining payload on the truck (for pin or tongue weight), etc. Combining the advice of those above, 1/2-ton trucks, with VERY few exceptions (such as the Ford F-150 with EcoBoost, MaxPayload and MaxTow packages), are not suitable tow vehicles for fifth wheel trailers. You even need to be careful of the loaded tongue weight on a travel trailer to keep it within the payload and hitch capacities for your truck. Dry weights - especially those published by the manufacturer - are near useless. The "payload" on the door sticker on your truck isn't even reliable because you don't know what your truck weighs with full fuel, occupants, hitch and "junk." The CAT scales are your friend...
Rob