Just picked up a set of straps from Fibersteel for the rear clam of my Beck 550. On the cabin side of the car (not the rear decklid), there is really no good place to screw the bracket down as the fiberglass in that area is not a single layer when approached from the engine bay, it seems. It's MUCH thicker than the provided screw is long and I certainly couldn't secure with a nut with the included hardware. I took the leather trim panel off on the cabin side and it's not accessable from inside the car. How are you guys attaching these straps to your cars?