An alternative to your pretty knot is to just wrap the rope through your webbing loop 2 or 3 times, rather than just passing the end through once - all the tension comes onto the wraps, and any simple knot like a half hitch backed up with a second slip-knotted half hitch or whatever
you like will hold just fine, and be easy to untie.

I do that all the time when I am hanging food packs or tarps or whatever - just hung my hunting camp up Saturday, hoisting the heavy pack up into a tree using 1/8" diam nylon cord - end of cord gets wrapped 3 or 4 times around the attachment point, then finished off with a couple of half-hitches.  Never have any trouble untying the knot because there is never any tension on the knot itself.