John,
That's a good idea! I fact, it might be even a bit easier than you describe.
Since two sides of the hole are flattened, I should be able to file down a nut with a right-sized thread, press fit it into the hole and just use a spot of JB weld to secure it so that it can be later removed, if necessary. I don't believe that it would be necessary to remove the wheel to get this done.
Does that sound reasonable?
Thanks!