When I've set up adjustment-free quick-change wheelsets on 6-bolt rotor hubs I've shimmed either the rotor or the locknut outboard depending on what's been needed.
Haven't seen any rotor shims for centerlock. Unless you can find some, your best bet is to shim the locknut outboard on the hub that has the rotor mounted wide.

DON'T try sanding the rotor down. It's unlikely to end well.
If nothing else, it'll take a lot of useful life out of the rotor.