[aerohead]

Originally Posted by jeremy128

Couldn't you rig up something that the flow of air over the car would inflate the tail?
EDIT: missed the last page before posting this. Oops!

Even with the pressure of an inflation pump my boattail wanted to dance around behind the truck.I had to add a cantilevered strut and band around the envelope to capture it in order to "quiet"it down.The periodic shedding of vortices create significant oscillatory deformations without a lot off rigidity.Goodyear's inflated airplane can give you a good working example of good (no pun intended ) design.