you can sand it and paint over it .i painted air plane frames . all were tubes smaller then 3/4 moly tubes were a big pain in the a$$ my friend that builds planes used polyester poly urethane ppg durathane went to powed coat they look very good and the powder gets every were the paint was abit tough. as for powder with a abit of orange peel i can not see why you could not step sand it up to 1500 or 2000 sand paper and wheel out the spots you see or wet sand and clear the out side of the rails? and sand and wheel