My set up:
I like a removable mid-rise topper - I want some headroom & as needed I can remove the topper, so no permanent furniture/fittings . I use a Roll-a-Cot (shown previously by other posters), a Thermarest pad, and sleeping bag. Topper has opening and screened windows. I have a 12vt fan and LED light wired in - the light is at the tailgate and pivots...lights the interior or the tailgate area - which is the table. My camping "kit", clothes, food, and other junk is stored in plastic bins (2 stackable bins, and an under bed bin). An Rtic 45 qt cooler sits in the rear seat area of the double cab.
I want storage that is easily removable, dust, bug and weather resistant - that if needed can be moved to the cab or stored on roof/ground and allows my camping kit to always be stored ready to go.
Two adjustable tent poles, some rope, and a tarp provide a flexible canopy system which can be mounted off the rear or side of the truck, or used freestanding, as needed.
Sometimes I haul a MC for more destination fun. Photos are Big Bend NP, doing 6 nights of varied backcountry camping and trail riding.