I thought a bracket on the brake hardware, but 1) the light would be buried under the bag, and 2) if mounted vertically, there's not enough clearance between the bag and the wheel anyway.
After staring at the hardware for a while, I think I'll take a scrap of sheet metal, screw it to the inner floor of the bag, and bring it out through a small slit. Then cut/bend it so it points up, and screw the blinky mount clip to that (instead of to the sleeve that would go around the seatpost). Maybe I'll find something already bent like that in a junk box. That oughta do it.
The problem with a tab or loop on the bag is that you can't really adjust the angle of the light. Just like when I clip it over the open zipper and it points down toward the ground.
Last edited by LarryMelman; 10-23-08 at 12:55 AM.