My buddies have rooftop tents on their off-road trailers which work really well for them. I almost went this route after I upgraded from a ground tent and then to a 2-person tent cot, but my wife and I wanted some more space, room to stand, and room for a "honey bucket" since she doesn't like to use a tree. Our solution was a Lifetime Tent Trailer, which is still small and light enough to tow behind a Samurai, Sidekick, or Tracker, yet big enough to sleep 2 couples comfortably and haul just about anything else we want along with it.
Here are some photos from Labor Day weekend: