Just file the goddamn dropout a little - stop overthinking a million ways to avoid it. There doesn't seem to be a single thing that makes this particular frame stand out from the tens of thousands of similiar 531 frames made over the years.

Your idea of doing a single spot with the dropout adjuster screw is an elegant way to try this out.

The people who say to just leave it are underestimating how much the crooked wheel will ALWAYS catch the owners eye just like a nagging wife.