Keeping the mesh windblockers on

[Overdrive]

This is true, and sadly, some folks will take the opportunity to pop those things out and run just because the opportunity was there. That said, the only time the top is down in my car is when I'm driving it. Remove the opportunity, and they can't take it.

[southernstar]

The problem with zip ties is that you need to remove the screens in order to clean the inside of the rear window. Velcro may not deter thieves (although the motion sensor in the optional alarm system will); otherwise, as has been suggested, just put the top up when parking the car out of eyesight.