[yeti]

Am no expert on magnesium, however using a bit of common sense here:-

The wheels are new, therefore the protection should already be in place and undamaged. So no need to worry about that. Furthermore, I think I'm right in thinking this is purely a cosmetic paint job.

Suggest you can carefully flat the original painted surface taking care not to go through it, then paint over the top with any paint that doesn't react to whats already there.

Shame you are so far away, we could have done it for you for not a lot. It's not a big deal.