My beautiful paint skills here.
The orange is the false crotch paracord, tied around the tree at height with a ring.
Purple is your preset line, running through the false crotch ring, and then tied together on the other side of the tree. What's nice is once you have your climbing line pulled through the false crotch, you can then tie it to your quick link or tied loop on your climbing rope and use the preset line as your pull down line.
Blue is your climbing line after you've girth hitched it to the tree through the false crotch. Basically the ring is acting as a tree branch and is merely holding your rope at that height, while the tree trunk is taking your weight since your climbing line would be girth hitched around the tree trunk.
Your strap with a cheap bow hook would work the same way., it's merely keeping your preset, and eventually your climbing line, at that height. I would be careful of where you're girth hitch ultimately ends up on the tree.
In the second image, you could be putting load on the false crotch if you don't work your girth hitch high enough up the tree. Using the tail end of your climbing rope, and the tail end of your pull down rope (should be attached before pulling up the girth hitch!), walk backwards away from the tree and use those tail ends to shimy the girth hitch up the tree more.
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