It's been a while since this corrosion thead was started so I'll provide a follow up. As I figured that a powder coat job would be very expensive, I removed all the equipment from the boom then went to town with scotch brite pads in a pneumatic drill, cleaning the corrosion areas down to bare metal. Then I bead blasted the pitted areas as the pad can only go so far. After a clean water washdown, I treated the areas with an alodine solution. After that, several coats of Krylon gray primer was sprayed on then the complete boom was sprayed with Krylon white. Reinstalled the boom and everything is copacetic.