The US military used to have a jungle hammock that could be set up on the ground. If I recall correctly, the most recent version was the M-1965, but there were similar models from WWII. I did some googling but could not find a decent picture of one set up as a ground tent. Being military, it was undoubtedly heavier than a similar commercial model. And speaking of commercial models, at least one, the Clark Jungle Hammock states in its manual that it can be set up on the ground. Not being a hammock person, I have never owned one to try...