If the bags are going to be resting on racks, I'd have thought the saddlebag loops (or the twin-slot clamp thing that Carradice sell) will probably be ok, as there's not going to be that much weight on them. Otherwise putting the straps through the saddle rails will probably work ok, though it's not as quick-release as the SQR. I use the saddlebag QR clamp, which is effectively the clamp bit of a bagman QR, for my Camper Longflap in conjunction with a rear rack, and that works very well for me.