On thinking how "big brother" would make license plate frames illegal, why not LED's along side the car's already existing license plate lights that would either be on all the time or only be triggered on by the "paparazzi" treatment. I'm not so sure that the always on would be good as there's probably some DOT law about the limit of brightness so as not to distract operators behind you.
There's got to be a cheap and easy way to beat these SOB's at their game.