I hung my hammock recently in the usual testing of new gear, and for once I had someone around to critique my setup. The trees were easily 20'-25' apart, and we noticed an excessive amount of stretch in the suspension. I measured each part of the suspension with and without load applied. The ~20' section of amsteel that I use as a continuous ridgeline had stretched almost 2" over the whole 20'. It was more than I expected, but didn't account for the extreme amount of drop we were experiencing. My homemade tree straps (1" poly webbing) had stretched 3-4" EACH. I calculated that under load, the netting was increasing in length by 1/6th of the original distance from tree to cordage. All together, we were getting roughly 8" of stretch, and it was mostly coming from the tree straps.
So my question to you hammock pros is this: What material can I use that is as abrasion resistant as tree straps, but also very stretch resistant? I'm open to using doubled up cordage because I have never seen any kind of mark left on a tree from people using that method.