I honestly thought/think the rears dont matter. Its the fronts that show the driver in question. After all, limosines get away with it. MI can tint the windows in the back just not the front. You might find a loophole here Hugo. Because it was nighttime, cop may have thought it was same tint all the way around.
I know in FL, they carry around a tint meter and measure the % right in front of you.