If it is possible, it might work to link it to the steering linkage and have that push/pull it? There would be challenges: isolating it from the up/down motion of the suspension, and if possible, *not* moving the skirt for small steering inputs, and only moving it for sharp steering. At highway speeds, you don't want it moving.
Would you include a partial inner fender that kept the air from getting in behind the skirt?
Check out this car:
http://ecomodder.com/forum/showthrea...tml#post190671