I put a small (1 1/2 - 2 inch diameter) continuous loop in the whoopie loop.
I've taken to using dutch's whoopie hooks in the adjustable loop. I'm changing all my suspensions over to an inverted suspension.
Typically, the fixed loop goes on the hammock, and the adjustable loop goes on the tree straps via toggle, carabiner, or whatever. I turned that upside down, by using the fixed end on the tree and the variable end on the hammock.
I am putting small continuous loops or dog-bones on my hammocks for attach points. The fixed end of my whoopies attach direct to the tree strap with no hardware (usually I make the fixed eye right through on of the loops so its permanent, or, fix a sort of square knot by putting the fixed eye through the tree strap loop, and then pull the other end of the strap through the fixed loop so the whoopie is tied on). The other end with the adjustable loop has a dutch hook on it, which clips to the loop hanging off the hammock.
So all I do is throw the strap around the tree, put the free end of the whoopie sling through the open loop of the strap, and pull tight. Then clip the dutch hook to the hammock and adjust it. no toggles, no carabiners, no metal at all except the little hook. And no knots to tie.
For more info, read:
My personal blog
I would work it through as if you are pushing a drawstring back in hoodie.