Pictures are pretty much self explaining. Two slots in the strip are 18mm so the rubber will pass trough.
Added picture 8. Moved the weakest point away from the plastic parts.
Installed the Shad SH58X topcase (with backrest) using the original luggage rack and the Shad mountingplate. I had it installed twice. Initially it was too close to the buddyseat leaving too little space for an adult passenger.
Picture 1 - slots used
Picture 2 - extended two frontside slots...