Yes I have, Actually open tracking Cobra's. Of course in California there ins a greater number of Cobra's and open track events. The Northern California Shelby Club holds several open track events every year and there are many hot ladies who are actively involved in the hobby. Your best chance to see women driving Cobras or acting as pit crew members is at the NORCAL Mini Nats which is held every labor day weekend.
Here is the link to the Norther California Shelby Club.
http://www.norcal-saac.org/