If anyone can do it, Jay D, you can.
I can't claim to know much in the ways of tree-mounted bollard/winch systems, have messed with a few at tree shows, but never actually used one.
I have a 12V capstan rope-winch (power bollard) I got from a place called
surplus supply. I think it was built to go on a battleship or something. It will replace the 12V cable winch on my chipper. Maybe something like that can be used, like figure out the mounting system, get a pair of jumper cables, car battery and go to town. I only mention this because they say they will ship anywhere and it cost me somewhere over $300 usd, which isn't bad, considering.
OK, that may be stretching it a bit, the power bollard (but maybe not???) but if you will use a boat winch, I have a very good suggestion. On my biggest log arch there is a two-stage winch, one regular speed, and a second gearing in which the speed goes to half, the power goes to double and the direction of the rotation of the winch handle reverses.
The boat winch itself isn't all that much bigger than a normal one, but
it is the cool bomb. The high-to-low gear changeover can be done under load. Hope those links in the previous sentences help better describe what it is I'm describing.