As noted, look at the payload of the truck you buy. My reg cab C2500 has 3800 lbs of payload, my now sold crew cab diesel dually had 4100 lbs of payload per the door stickers. Meanwhile going back a few years, my 88 sw K3500 ext cab had 3000 lbs, and a 96 sw K3500 crew cab had 2600 lbs.
I would go after something with 4000 lbs or there about also. you will need 2400-3000 lbs or so for the hitch, two people and asst gear can be 400-750+ lbs or so depending upon the size of the people. 200-300 lbs for a hitch......
Marty