This traffic camera blends in with its surroundings: camouflage in plain sight.
atohms.wordpress.com
atohms.wordpress.com
It might help at night at least. What do you folks think?
Alternatively, you could cover your plate with a hyper reflective coating which would likewise overexpose the plate.
I don't know if this one is legit, but I've heard of at least one brand that is. http://www.photoblocker.com/
edit: traffic camera, not speed camera.
If my neighborhood were abused by pink-light violators, I might be tempted to post fake signs warning of a traffic camera. </confession>