I have tried flashing my lights at every A2 I see coming in the opposite direction for a couple of months - probably about eight times in total. Not one response from any of them but to be fair I am not sure the other drivers have time to react.
I quite regularly post in the 'Was it you?' section but have never had a response. I have been thinking about putting together small A2OC.net flyers which I would keep in the car to put under the windscreen wipers of parked A2's I see. The more A2 owners we can get using this forum the better!