So I have been running a overhead plate cover on car now for year or so and I have not gotten any tickets form the redflex cameras.
I had to adjust the plate off the car so it is 45* from level ground using longer screws and washers. I looked at the angle of the camera to the plate and keep moving the plate till it was blured out. This puts the plate far enough out so at night the plate lights are shining behind the plate and it is dark but so far so good.
I did have a LEO approach me in a parking lot. He asked me if I was planning on running red lights. I told him I would never plan it just happens sometimes esp. when the yellow light timing has been shortened for th camera to snap a picture.