It is kind of crude, but you can paint the inside of the curl with a piece of cloth attached to a long rod. Since you don't really care what it looks like, just wanting to get some protection in there. Just saturate the cloth with slow drying paint like rustoleum or POR15 and slide it in the curl, back and forth until the whole length of the bed is painted. You can still paint the open ends that are visible to match the body color and the rest of the curl is protected from rust. Be sure to wipe off excess paint because it may not be compatable with your body paint.
Stake pockets are harder and you probably need to spray them since they are more irregular and very visible. You can paint them from both the bottom and top if your bed is disassembled.
The electrogalvanized surface provides limited protection but is not intended to be exposed long term.
Mar-Ktech
