I missed an opportunity to buy the F522 hardware cheap from a member here, so I couldn't bring myself to fork over $128 for the new one. I stood in my shed (too much snow to back the bike out yet) and pondered a design for probably an hour, all told. Here's what i came up with. I realize that it looks a bit ghetto, but I think some judicious sculpting (rounded corners) and high-quality coating (spray paint) will clean it up nicely. It's good and solid, and Jolene really appreciates the backrest (temporarily attached with duct tape).