Aye, dont put it on the roof. I keep a fresh Jack in the Box styrofoam head on my antenna it doesnt flop around so much with it It looks a lot like this
Makes it easy to find in parking lots too.
99 Cents at participating Jack in the Boxes....
But seriously, try one of those Billet Antennas, they are very stiff and dont flex much. That might work and she can still put Jack on top there.