It’s not technically difficult, just a little time consuming.
Remove wheels
clean well
remove all wheel weights (you can mark location on the tires to replace in the same location) scuff/sand entire surfaces to be painted
Carefully mask off the tires for overspray
Quality epoxy or etching primer on any bare metal surfaces unless you’re using a quality chassis paint that has bare metal adhesion properties. (But generally won’t have as good of UV resistance). Should use a quality Urethane Enamel
Any touch up sanding or prep needed.
Couple 2,3 coats of paint
Watch paint dry
Replace wheel weights or get re-balanced.
Done!
Depends how long you want the paint to last. You may get several good years out of quality rattle can paint, especially if the rv is protected from the sun more than it’s out in the world.
But assuming you’re not setup to paint with a paint gun, you can buy better quality spray cans from autobody suppliers. They will be very expensive for what they are but cheaper than a gun and compressor for a one time, small quantity like a set of wheels.