I saw this video on another thread this morning:
(I hope that worked. Never tried it before.)
Anyway, I was wondering if it would not work to sew a loop into the end of the tree strap with either the adjustable or fixed loop of the Whoopie Sling going through it according to your taste. Then you could use this knot on the tree strap using no carabiners, soft shackles, etc. The Whoopie would be permanently attached to the strap, so you could not leave your straps wrapped around the tree as you merrily go off down the trail, and there's no toggle to lose either. The only drawback I can see is for the gram weenies who take different length tree straps according to the diameter of trees they expect to encounter in a certain region. Seems like you could have a shorter length attached, then take more straps with loops to interlock to account for larger trees as needed.
I use a double-ended stuff sack for my hammock & suspension, so this would work to start at one end and stretch to the other while holding your hammock up if there was wet ground, snow, etc.
Questions? Comments? Snide remarks?