I think I've seen the 5/32" rod at Ace hardware in the dowel area.
Many hobby shops (RC Airplane etc) carry it too. Call ahead and save gas..
Nope, I also agree that coro is not going to be firm enough to hold it's shape
when under windloading.
If you were to use it to make some small air dams for the tires, it might be
stiff enough, if you put the corrugations going vertically.
(It's much harder to bend in that direction).
I've been thinking of making some for my tires, but can't decide on what size they should be.
This one only looks about 3" tall..?.