I fitted my steps as-is and, while in place, marked where they bear in the plastic. Then I took them to a powder-coater who beaded any rust off of them before masking and coating them. When I got them back, I wiped the bare area that had been masked with gun oil. When I installed them, I cleaned them and gave them a final application of oil (fingerprints aren't just oily and can leave contaminants that start corrosion). The steps on my RV-6A that were just coated with primer have shown some areas of rust where the primer has worn thin, easy to remove and re-prime. However, I have been using the steps on the RV-10 while working in the fuselage for the past few years and they show no sign of wear or corrosion.
Forgot to mention about the gear leg sockets. It should be fairly easy to remove any surface rust there and on the gear legs with emery paper. Then gun bore cleaner followed by a light oil application. Again, avoid fingerprints.