We have $20k, which used fiver under 29' that can dry camp?

There would be just myself and my wife for under 375lbs total. We took out the back seat of the crew cab and replaced it with a plywood floor with carpet for our 95lb German Shepherd dog. The truck is a basic XLT version with a/c, fm stereo and not much else. I would probably add 65lbs for a genset in the bed and maybe another 25 or so for a steel cage to keep the sticky-fingered at bay.