For my tether I actually try to climb first aand then make my tether the right length to fit my bodies natural distance during each step. If you make it to short it will make your climb 1. Take longer 2. slightly uncomfortable. if its too long if your bottom falls out it will make getting it back that much harder. I have used 550 for a pull rope but also thiker rope, the best thing to use IMO would be a stiff rope that doesnt tangle too easily and can support the wieght of whatever you're hauling. I've yet to perfect this myself because 550 tangles pretty easily. the distance should be around 25 feet. It'll give you a little extra playing room so you can get settled in b4 you start pulling up otherwise if it's too short you might end up climbing the tree and pulling your bow up at the same time. I've also done this. I would make it 5 to 10 feet longer than the average distance you expect to climb to give yourself that freedom of movement.
