cfg,
I was actually thinking about constructing some sort of discs like those brake dust shields, for drag reduction.
The ones you posted seem like a bit of a gamble if they would fit right. Not sure how easy it would be to trim them if they didn't... Plus they would probably look pretty silly? I wonder.
Found this wheel today, $86 per wheel at wheelmax.com is almost too cheap.
Getting better at gimp:
And with other mods.