Update!
I'm trying not to buy anything since my move-date is so near, but I found a use for some scraps that otherwise would have gone to the recycler.
The wheel-skirts are made of some bits of scrap aluminum sheeting I had, patched together and reinforced with some aluminum flat to hold it away from the tires.
Replacing the tire might be more annoying now, but it's really not much more than a few screws.
