I think 0,5 mm washer should do the trick. This is probably how much I need to compensate for that manufacturing defect. It shouldn't affect the frame spacing. The other alternative is to use a small file and make that hole in the caliper a bit wider so there is more room for the bolt. This should maximize alingment possibilities.

 Put a washer on the end of the axle hub to space wheel further away from the frame to give you a bigger gap

 Smaller hub spacing than frame recommends?