I've been looking into getting a hammock instead of a new tent. My biggest concern (this may sound silly) is how well it holds it's place on the trees. Sorry, this may be really stupid question, but I have a concern of the thing not attaching firmly to the trees, and sliding down to the ground once I get in the thing. I'm a fairly big guy....around 240 lbs. Is this something I should be concerned about? I'm really not very familiar on how these things attach to a tree. Also, because of my size (6', 240lbs), would there be a particular hammock that would be recommended? I notice that Hennessy has a couple that are rated to 250 lbs., but I'm wondering if I would be pushing it in using one of those.