Re: Installing new deck hardware for a dummy.
I agree about the fender washers. You need to analyze the loads. On most deck hardware, the load is in shear, especially for cam, clam and sheetstopper clutches. The backing plate is only there to avoid the tightened bolt/locknut and nut from digging into the fiberglass below.
Stu Jackson, C34, 1986, M25 engine, Rocna 10 (22#)