Using aluminum foil to paint parts works well also, it can cling and wrap easily. also instead of using expensive dynamat or foil back rubberized sound deadner, go to your local lumber yard and get peel & stick flashing tape/window wrap or roof patch, same stuff just thinner and not as wide, heck put on two layers and still save a ton O'money.
For rusty crusty parts try electrolysis rust removal with your trickle charge, works while you sleep and is super easy.