This may not be the right thread to post in, but I'll give it a try.
My right-brained-over-think-everything engineering mentality might be taking over, but I am trying to switch from a tenter to a hanger and the only big downfall I can see is not having trees (stay with me here). All of you other engineering minded persons, forget about everything but the concept.
Make 2 inverted V's, hang your hammock between them making sure that when hung the V's have an outward angle of X (30-45 degrees). When the weight of your body is in the hammock, the force is being applied "down". making the outward angle of the V's work "with" you. The angle that the V's are affixed to will account for your swing stability.
Not sure if you understand that, but set aside anything else, will this concept work?