ok. I have the NON-step version from duffs and they mount with several riv-nuts along the top/center but the end attaching points are bolted through the rear quarter and the front fender. so those two areas can get a large washer/piece of plate put behind it for support. also if your front fender is steel that will help too. for the other bolts, I would not use the riv nut in FG in that area for fear of pulling out of the glass. I dont know how the back side of that tub looks but I would look at opening up the back side so you can get a long threaded plate in there or maybe drill holes all the way through so you can put sleeves in each hole and a long plate on the back side to be able to mount it all snugly