Tonight I continued work on repairing the back door.
I removed the clips that were holding the two panels down toward the center of the door. They seem to be on there okay now.
Next up, the large panel that goes toward the top of the door.
I whipped up another batch of JB Weld and applied it with a toothpick around the edges of the panel. For those that wish to emulate this technique, the toothpick is from Lucille's BBQ. (I'm kidding about emulating, but the toothpick really is from Lucille's.)
A short while later, I had the perimeter covered. Ideally, I would have kept the JB Weld away from the very edge of the panel to prevent it from oozing into the panel seam with the skin, but I didn't always manage that.
I clipped and taped the panel down onto the door, and afterward used a toothpick to scoop out some of the JB Weld that did end up oozing into the seam.
I'll let this dry overnight, and then work on the middle panel.