I just took a chance and made a pair of whoopie-slings that adjust out to 15 feet each.
They still roll up lighter than my strap/cinch buckle and carabiner setup.
I get the feeling they will last longer too since the straps I use with them will be shorter and only used to grip the tree. They seem to hold way less water than the tree strap setup I've been using for the past 5 years. No more soggy mess dangling from my ruck after hanging in the rain.

I don't think I'll ever use them at their maximum length of 15ft until I get a portable ladder, but they adjust down to about 1.5 feet short so anything between that distance is usable. Remarkably strong grip too...that was completely unexpected. My coworker and I couldn't make them slip with each of us pulling on the ends of the whoopie sling.