Can anyone advise me on using dissimilar metals including fasteners to attach brackets to a vehicle body? My concern is that galvanic corrosion would take place sooner than later

Materials:
Brass flat-bar - side skirt brackets
Stainless steel Inserts nuts (riv nut) - used one side to rivet into the car body & another into brass flat-bar
Stainless steel machined screw - used to fasten the bracket to car body on both ends
Car body - factory treated sheet metal

The reason I went with stainless steel hardware is because these would be exposed to the exterior elements / mud, dust, puddle splash, sand, rain etc. I was thinking perhaps once I have fastened everything just to give a coat of protecting wax on all the hardware. still worried about the galvanic corrosion taking place? I do stay near the ocean. One part of me is saying just do it and hope for the best as there will always be corrosion while another saying hang on and find out what is best so you don't run into later issues?