How about drilling a hole in the side of the door for access to doorhandle nut?

should be fine if there is not one.

Pull the door panel off.!!

ONLY USE KROWN LUBRICANT ON ALL DOOR HARDWARE. EVEN GM USES KROWN OVER THEIR CRAPPY LUBRICANT. The GM Lubricant doesn't creep up hardware etxc, inside the doors and locks like KROWN.