A local commuter relies on his seat-post mount - it is frequently covered up by what he has on the rack. I just want so badly to stop when I see him (when I am driving - he rides in later than I do) and tell him, but never have. I have mounted my lights on my trunk, my backpack, and my helmet, and have a steady red on my rack. You might find you can use the P-clamp approach and get lights on the rack legs. I zip-tied my PB Superflash to the trunk by just tightly zipping to the basic mount.