Guess I will answer my own question – spoke to Neil at BMW Experience today and he was very helpful. The only solution is to mount the box using bolts/spacers provided in kit form by BMW for this purpose. Probably means drilling a hole in the box. All under warranty. Seems like BMW haven’t found a solution and are not in a hurry to do so. if you ride a GS1200 with a top box – beware you have a potential projectile just waiting to launch off your rear end and seriously injure someone riding/ driving/walking behind you ! Se the ADVrider forum for more details (or UK GS forum) !