Yes. Almost the right answer, but for the wrong reason. The scuff (about the size of a quarter, by the way) was below the license plate. The burnt-through wiring was hidden, resting up on top of the muffler on the right side.

FWIW, the lights started working again shortly after my last post last April, so even though I had my doubts, I figured maybe the dealer really HAD fixed it, and I stopped worrying about it till it cropped up again.

 

Had a similar issue with my focus! Short in the license plate lights. I got lucky and found it within about 20 minutes if looking the car over though.