Are tasers, mace and tear gas allowed there? I know it is nearly impossible to legally carry a firearm or even an air gun there, but there has to be something.
This might be a chance to use the home-made dog repellant used by bicyclist
Get an atomizer (Spray bottle) and fill it with 7 or 8 drops of liquid dish washing soap, 2 table spoons of ammonia and top it off with tap water.
The stuff works like tear gas and will put even a large mean dog on the ground for 3 or 4 minutes. I have never used it on a person but Imagine the effect would be compatible. Put a mist of that into the eyes of anyone approaching your car and then ask them a dollar to spray them again.
If challenged by the police it is just soap.