RE: Gun Sling
A tree stand hook and a looped rope located above your head can make a good rest for slug gun ranges. I usethem sometimes in stands where I can see less than 150yds. Not the most solid, good enough for a short shots though. Beats offhand or slung by a mile for me. I wont take(or cant always make)a true offhand shot past 70 yds or so. A crude rest can make anyone a much better shot. I have a couple "tree house" stands on power line cuts, 400-500 yds each way. I have a dang near a benchrest shooters outfit in those.
Try shooting alot offhand(standing), you might be alot better than I am, but I was shocked by how bad I really was! Sitting or prone is much better, but its hard to get situated in a tree.