That's another one of my designs that fully escapes the average person until they install a set and start to understand just how elegant the design is. Overbent by a couple of degrees so you can preload them. 1 degree bend just down from the top edge to compensate for wavy sheet metal and close up any gaps plus that makes the top edge of the backer behave and bow to my will, not the will of the sheet it was cut from. Ample small fasteners to spread the load out as much as possible across the sheet metal so point loading is minimal.
Yeah, I know, it is just a rock rail but I put an inordinate amount of thought into the design to solve all the problems I've seen over the years with rock rails.