For a spacer perhaps you can cut a piece out of a nylon cutting board and shape into a wedge to suite. Not sure how durable it would be in that particular application though. Since I bought a cutting board years ago to repair the window rollers in my D1 I've been finding all sorts of uses for it.
Also where I've got bolted connections between dissimilar metals I've been replacing the washers with galvanised ones. If anything I'm hoping it will mostly protect the bolt because I pulled a lot of heavily corroded ones out but potentially it could help for something like door hinges.

