is there any reason why I shouldn't use an anchor shackle as a pulley? If i'm pulling a tree over, and the bull rope is going through a block on another tree and back through a mid-line bowline for a 3:1 pull, I want to put the shackle on the bowline so there's no rope friction at the bowline. Something like this has a 6500 lb WLL. And it's only $27. Why not use one on the anchor point also?