Modern problems require modern solutions. Not having a trail I don't know what kind of room you have under the tray. But food for thought when i repaired airplanes a common repair was a flush repair. All the support was beneath the skin with a plug attached, I wonder if you could place those straps under and screw the plug with 2 small screws into tapped holes to hold it in place? I can do a quick mock up on my phone if you need a visual.