Correct spelling and punctuation oftens helps, they hate that
The rear camera is a marvellous idea, especially if you can find a cheap camera which records straight onto an SD card. A bit of clever wiring (or not so clever fiddling) to allow you to turn the camera on and off from the front as the camera looks out the back and you can get yourself some hard evidence of the annoying lil tikes.
Tow bars are also very good. I was in a rear collision a couple of weeks ago with a Ford Cougar. My car was pretty much untouched, her car though was not so happy with a busted front grill, bumper, bonnet, radiator and potentially chassis damage. I love my tow bar.
Alternatively, de-cat your exhaust system, run your engine a bit rich and shoot some flames into their radiator. Some people get so bored after the pubs kick them out.