I used to boondock over 25 weekends a year in my 95 Dakota with fiberglass shell. A few very simple (perhaps obvious) things that made it more comfortable for me were:
- cedar tongue and groove (closet lining) down the center of the bed liner. Smoothed out the floor and kept my bed dry when my rig popped a leak one night.
-Having a slider window through to the extra cab on my truck. That allowed me to keep some of my stuff in the extra cab and get to it without leaving the bed, making more room in the back. Also works with a reg cab, you just have to move stuff when you park. If the shell doesn't have windows or a vent, a slider also lets you use the cab windows to ventilate.
- 2 poles and a good canvas tarp. This was a cheap way to make a tent off the back of the shell. The poles took the strain off the pneumatics. Drape the tarp and stake it out. Close the tailgate and you have a stand up changing room/ shower room/ private place for the bucket pot.
- My shell had screened slider windows, so I installed wire shelving inside that covered the open part. That allowed me to leave the windows completely open in the summer without worrying about someone ripping the screen and grabbing stuff out of the back.
- I 'glow snowed' the inside of the shell with glow in the dark paint and hit it with a flashlight before going to bed. It looked really cool, but the purpose was actually to keep me from cracking my head on the roof if I sat up in bed. Cheap and 80s cheesy, but it worked for me