When I was in Nam we found a lot of the NVA carrying hammocks, these things would fold up to about the size of a pack of smokes.
I've never tried a hammock for sleeping in the woods but I've heard claims that if you ever use one you will never sleep on the ground again.
I always used my old cowboy bedroll and was lucky in the fact that where we stayed nature provided us with some type of insulation from the ground.
However I don't believe a cowboy bedroll would be the thing to use if you are wanting to travel light.
Best Regards
Bob Hunter
www.huntercustoms.com