rust protection on new bumpers

Hello FABO, Im getting ready to mount new AMD bumpers on my freshly painted Duster, i would like to paint the backsides of the bumpers before i mount them to keep them looking good on the backside.
So far i scuffed them with 80 grit and then i was going to spray some 2K epoxy primer and then top coat with something just not sure what paint to use yet, im open to suggestions.
Im not sure if what color either, black or some variation of silver/aluminum ?
rattle can over epoxy or break out the paint gun?
any suggestions would be appreciated...Rich