Those same carabiners, though, will also clip to webbing & buckle tree straps, which can (theoretically) crank tension into the single line (as much as a man can do in the field and at 6+ feet up a tree).
I got my giant SLS whoopie built today and just came in from the back yard where I began the experiment.
Apparently, even Amsteel needs some stretching: I finger tightened the giant whoopie attached to my regular tree straps, which, attached to the giant whoopie are more perpendicular to the tree, right? There was some deflection of tree straps at the tree when I loaded the hammock the first time but then I could also finger tighten the whoopie some more afterward. After three times I got almost all out of it that I could and had a fairly tight hang.
It was getting dark so no pictures this evening. But hopefully, tomorrow I'll crank some tension into it with ratcheted cargo straps. The key to this whole theory of mine is getting enough tension in the giant whoopie to minimize deflection, thus making it behave as a horizontal tree limb (purlin) with carabiners sticking out of it for hanging the hammock with the regular whoopie slings. It is a whoopie structural ridge ridge line parallel to the hammock structural ridge line to from a trapazoid. Once you have the trapazoid you can calculate the adjustable system across three parameters while preserving the 30* hang angle ... I think, if my math is correct.
I'll plan to get pictures tomorrow.