On my VFR800 I had Givi trunk and saddlebag mounts, but didn't like the big hard bags on it when out on a day ride playing. I took a piece of 1/2" plywood and made the appropriate cuts in it so it would engage the forward mounts of the trunk mount, and a small square cutout for the latch to stick up through. I drilled one hole through the plywood and the rack in the location that the electric interface goes on the trunk (which I did not have) and put a single nylon bolt (an unused toilet seat screw) down through both holding the plywood to the rack. I permanently mounted a nice looking soft tail pack I had bought for the purpose to the plywood.
It wasn't as neat as a self latching bag, but it was pretty easy on and off with one hand tightened screw. I'll try to dig up some photos later.