convertable window tinting

I am looking to tint the window in the back of my 1995 3series but i am having a hard time figuring out the right way to do it. Do I replace it with already tinted pleixy glass or do i tint the plastic itself?

You can't really tint the rear window because it FOLDS when you take the top down. The tint film will peel off and have bubbles and look all jacked up. If you can find a tinted window already (smoked plastic, not tint film which would peel off anyway) that would be better.

thanks i was looking on the internet a lot but with out the correct termonology i wasnt finding much. Maybe now i will find more sucess.