I don't/won't put a lock-on any lower than 25' and I won't use my climber less than that if I can get up a tree that high or as close to. Just my .02 cents, but have been busted lower too many times.
I just finished up putting out my last stand for this year on Friday and the 30' pull up rope had 2 feet touching the ground when I was done. I had it tied off on the seat frame.