I would sand blast them and if structurally sound , use bondo to fill and smooth the surface and paint with a good epoxy paint
after you paint them wrap electrical tape around them. they do that to bicycle rims to keep the spokes from digging into the tube.
They were sandblasted and are solid. I think the pic makes them look worse than they are. The rust on the one pictured is the worst and only affects about 1/3 of the rim. The others aren't nearly this pitted.
I picked up some rim flaps from Speedway but how in the heck do you mount tires and tubes with these things?????
Use baby powder liberally on tube and flap. It helps minimize the pinch