Every taillight I've owned has mounted to the seat post, but when I load my rear rack the seatpost light is no longer visible. Instead, I'd like to mount a light to the rear of my rack, which has a single centered screw hole for mounting a light. What kinds of lights can I mount with this kind of setup? Are there lights specifically designed to be mounted on the back of a rack with a single screw?
The best picture I can find is below: