I use a blackhawk serpa paddle holster. The paddle fits over the waist strap and if I dump my pack I can just slide out the holster and put it on my waist. I have the kifaru tline so it actually fits over that smaller strap and not over the actual waist strap.
I use the blackhawk serpa with the belt loop attachment. I take the buckle off the waist belt and install in with one side on either side of the strap stay next to the pocket. I have mine setup on my left side for a cross draw. That keeps it out of the way and it doesn't move around.
Holster arrived in the mail today. Looks like the cats meow for me. It will hold a varity of arms from autos to revolvers. Works great for my Glock 27 and will work for full size guns as well And can be worn on either side. I'm very happy with it.