Leave it sun, then heat up the whole item additionally with heat gun, then rather quickly paint the whole item. Does not have to be too hot,,,would be good if RPM would suggest range of appropriate temperatures that one could test with one of those laser heat temp guns.

I would not overheat a MC as could be possible to damage seals I suppose. Some heat guns can generate a very high temp.

If you install MC and other underwood items, likely a drive of vehicle would heat up to sufficient temperature to make RPM happy.

Final finish will always be a bit duller than natural glint,,,,somewhat as a clear coat,,,not bad just a bit different.