I dont agree with what your doing at all but I figure if you are really determined to do it you wont care what ne one says. That being said Polarized lenses are actually an amazing thing, you might have to dig on the web a bit to find the right thing but if u can get 2 polarized pieces of plexiglass or glass or plastic (not sure if plexi glass or plastic can even be polarized) and u put them together poles reversed then nothing can be seen threw them. So if u have only one sheet on ur plate it would ust look like a tinted cover, then somehow fashion a second piece, turned the opposite way, to fall on the 1st then Kazam no light passes through making ur tag blocked. I probly didnt make any sence just now but it does work.