Found a hardware store with 5/8" stainless steel FLAT washers...anyone had luck with these? I guess the outer diameter isn't as big as a fender washer? The OD on these are 1-1/4". I think this might be large enough, but just thought I'd check. Couldn't readily find anyone else trying these when searching the thread.
EDIT: Sorry I take it back. I went deeper and found this post
. Said they worked fine for him.