i am going to put a soft topper on my colorado, the ZR2 4 door only have a 5'3" bed, but with the tailgate down, there is still plenty of room for me (i'm 6' even) and with the soft topper, it will be a pretty good truck camping setup. i may get a canvas cutter for that too, if you sleep head toward the cab, an overnight shower wouldn't be a big deal. i like just sleeping in the bed with my sleeping pad and bag if it's for sure going to be dry, it's not bad at all.... it's easy.
if the soft topper isn't practical (like lots of rain) i will just pitch my shelter close to my pickup, or throw my pad and bag under my pickup if practical.... i would have done that Thursday, but where i had to park was wide spot with melting snow which made for some nasty clay like mud, so that was a no go in that situation... my camp shoes were ankle high xtra-tuffs by necessity.
pickup camping should be kept simple. a buddy and i rigged a regular cheap tarp over his pickup bed a couple times pickup camping in the rain... drape it over part of the cab, close the corners of the tarp in the back doors of the pickup, than use tie outs where you need them to give you decent shelter.... cheap, easy, and works fine.... we stayed dry in some pretty good rain