Damn, that's a lot of choppin' steel! As far as the quick-draw goes, I generally try to steer people away from retention straps of any kind, but quick-draw is actually a little easier for me. Have you tried using a wide flap (like two inches or more with a two-snap closure) instead of just a small strap? That would resist some of the stretching you've seen.
You are a genius! :thumbup: