Since this bed bolt & hole are already damaged, I welded some splines onto the bolt, sharpened them with
carbide Dremel bits, and then matched those locations in the bed hole with a triangular file.

The bolt won't spin again, but it can still be installed & removed as-intended. Before final installation, I sandblasted & sprayed it with cold galvanizing, similar to its original finish.
IF THE IMAGE IS TOO SMALL, click it.
I have since decided to swap to later-style bolts from now on, as shown on this & the NEXT 2 pages:

This page shows how to swap the bed bolts to the newer style that's easier to R&R: