Originally Posted by
uciflylow
I have my lights mounted to a pice of 1 inch PVC pipe that is held to the rack by 2 pipe clamps. The lights are then clamped to the length of pipe just as if it where the handle bar.
+1 for this. I've found this to be the easiest way to mount lights with a handlebar-type mount anywhere other than the handlebars.
For lights with screw-type mounts (usually generator lights) you can use a p-clip, a long screw, and some spacers to mount the lights off the rack.