I did all 5 of my steel rims with Urethane gloss black. Before the gloss black, epoxy primer, then epoxy sealer. Go as thick as you want. Urethane is so sticky, there is no worries at all about bead problems. All 5 of mine have been holding air for months now. Nothing to worry about if you prepare the metal correctly in the first place.
Not to argue with you, Deve, but the problem we encounters was not leakage, but rather than the paint was simply so thick on the wheel that it increased the diameter enough to prevent the tire from even seating. no matter how much lube we put on it, and how much pressure we went (we stopped at 60 psi), the ties simply would not seat. After grinding down the paint, tires went right on. With the method you describe, maybe 2 coats of each, should be fine and not cause any bead seating problems.
