To slow or stop corrosion between sandwiched metal surfaces, you could use a 50-50 solution of spraying thinners and fish oil compound.
So, my suggestion would be to do the work in place: sand blast, vacuum, then liberally paint the solution along edges and in any places you cannot get a paint coating to. You will find it is as good as WD40 at getting between surfaces, but once the spraying thinners evaporates, leaves a reasonably hard surface that excludes air (so no O2, so prevents/slows further corrosion). Wipe away excess after initial application, from surfaces you can get paint to. Wait a week or so, and then paint what you can get at.
Works really well on door skins, inside doors, and so on. I also used fish oil straight on battery terminals: leaves a tacky surface but slows terminal corrosion markedly. Don't use the 50-50 solution for that application: it will get between the terminal and post, but straight fish oil is much thicker and works well.
Just a suggestion.
Mike