Not gonna ask you how you got salt water up and in there. Ah what the heck, how'd you get salt water up there?!
It may be possible to save the brackets if they are still mechanically strong. Phosphoric acid will change the rust from ferrous oxide (rust), to ferric phosphate. Dilute phosphoric acid (called rust converter etc) is available at most hardware stores. It is also called metal prep and is used to acid etch aluminum prior to painting.