I usually just sleep in the back of my rig since I am usually solo.  About 7 years ago or so, I sold my full size pickup and went with an Xterra.  I loved being able to bonzai to a trailhead or hunting area, climb in the back and go to sleep, ready to go in the morning.  I totaled my Xterra, and replaced it with a 4Runner, which I can do the same thing with.
  However, sometimes I do like to have a more comfortable camp, especially when I'm hunting Nebraska for a week, or going with other people.  
  I went with an old M101a2 army trailer that I got from a government auction.  I got all the rust and old paint off the frame and underside, repainted everything with rustoleum implement paint. I had a guy in Denver make a custom canvas cover for it and I made the bows out of 3/4" conduit, so the roofline pretty much matches the height  my 4Runner.   I put a BedRug bedliner down on the inside.   Im keeping it pretty simple and utilitarian and really just using it to haul my camp. I didnt want to put drawers, rooftop tent, water tanks, etc. that would diminish its use as a utility trailer if I ever need that.  But, I can haul my 10 person Turbo Tent, bathroom/shower tent, full camp kitchen setup, cots, heater, coolers, batteries, propane, etc.     This set up has been working well for me with family camping trips.   I can have a comfy camp set up in 30 minutes or so.