Next I'm going to paint the cutouts in the rear wheel ... without removing the wheel ... not sure how well I can mask it and maneuver the can of spray paint for that

It's really easy to mask it off. Place wide pieces of tape onto the surfaces you wish to protect, that over hang the edge to the areas you want to paint. Using a rubber mallet, tape on the edge, this will "cut" the tape. Presto! It 's the way I was shown to mask off an engine block.