Further......I have used a product since my youth call "OSPHO" for surface prep in rusty metals. It is basically phosphoric acid. It is a little much to breath in and can sting a bit on exposed skin but it does an awesome job. I just chip and wire brush off all the loose rust, apply with a spray bottle or brush, wait 24 hours, and used it as a primer. I may give your suggestion a go to see if if it is more user friendly.
Any suggestions for a finish coat for the blade side of the deck that is more durable than regulator paint?