We were fussed at in a Florida State Park. A couple of days into our trip my wife was at the camper, and the ranger came by and told her that "you can't encroach on the vegatation." My wife looked at him and said "What". He got said it again, my wife couldn't figure out what he meant. He got frustrated and started pointing at the hammock. My wife said "do you mean I need to take my hammock down?". He said yes.
We laugh about it all the time. We didn't mean to cause trouble, but it was really funny to use encroaching on the vegetation as a way of saying no hammocks. He had been trying to track us down for 3 days, he could have just left a note asking us to take down the hammock.
I've seen some people rig up and A-frame on each end of the hammock with a rope going back to an anchor in the ground. That would be portable, and not take up much room.