Remove rust inside door panels?

I'll be starting the work on my '75 Dart Sport doors in the next day or two, and since my doors came from a salvage yard, there's definitely surface rust inside the door skin. What methods do you folks use to remove the rust, or do you use one of the available encapsulation sprays and call it good?

I'm sure I'll need to remove the window regulators (once I figure out exactly how), but even then, there's not an easy way to get in there to sand by hand.

Thanks!