In Oz, we used to buy plate covers made of plastic that would only allow viewing of the plate from straight on.
Problem was that on the highway, the cops would overtake you (or vice versa) and notice the invisible plate from an angle. Then they would fine you lots of money. :-(
Problem was that on the highway, the cops would overtake you (or vice versa) and notice the invisible plate from an angle. Then they would fine you lots of money. :-(