What makes you think some of these guys won't just whoop your butt???
They want something with my butt, but I'm not sure whoopin' it is what they're after.
If anyone had the will or the cash, they have car alarms that will notify you via remote that your car is being broken into. You could basically set up a sting - a good old fashioned ass whoopin' would be good justice.
I've seen cars with no license plates at some trail heads. Seams like a good idea - what are they going to do, hang around and wait for you to come back?
Also, this way Mr. Randoms don't take your plates.