I would worry more about progression of the rust. Usually water inside the door causes rust there. The doors are supposed to drain through holes in their bottoms, but if they don't drain the humidity will rust from the inside out.
I'd certainly take the inside panels off and clean and dry the insides of the doors thoroughly. Disassemble as much as you need to get any moisture and debris out. Make sure the drains are clear and any rubber or fiber rain seals are in good condition and in place. After removing any loose rust and debris, I'd paint over any rusty metal on the inside with a good rust encapsulating paint like Eastwood, POR-15 or Rust Bullet.
To fix the appearance of the bottom of the door, you could grind out the rusty metal and either glue metal on the inside or fiberglass to span any holes in the metal. Then fill from the outside. Body filler is not meant to be a structural repair, so you need some structure to back it up before you fill any voids.
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
ECO Green: '15 FCA Jeep Cherokee KL Trailhawk
Last edited by tgreese : 06-21-2009 at 10:32 AM.