Well, I have all sorts of ideas on how to fabricate a mount. I just have to decide what kinda stuff I want to put back there. PVC, wood, plastic, metal, all could be shaped and attached so that virtually anything could be attached. I even have some ideas on fabricating a platform that can be velcro strapped on and off the rack, letting the lights hang off the back but below the rack, so that an entire array of lights and blinkies can be put on and removed with ease while still letting the rack be used for a trunk bag or panniers. I guess I will design something once I have decided what I am going to use for tail lights.

But I still find it hard to believe that at least one tail light doesn't come with a bracket to clamp onto the tubes of a rack.