We were talking about this because we too carry a hammock with us, but so many times we're camped out in the desert with nothing to hook it to.
I was thinking it would be easy enough to attach one end to our bike rack on the front of the camper, and pull the truck forward about 15' and attach the other end to the upper section on the back of the truck.
Since not all trucks are this way, I was brain storming one night and thought it would be pretty easy to make a piece of pipe that could slide into the back of the trucks reciever and extend up into the air.
You could have another section of pipe that could slide into something either on the front, or the back of the camper depending on how you're parked.
Obvisously this would have to be custom fabricated, but that's all the fun of it. We too carry a bunch of rope with us, because not all camp sites look like this