If we're going by the "plain view doctrine", you can cover up any item in your car with e.g. a blanket, and an officer would not legally be able to move the bla

If we're going by the "plain view doctrine", you can cover up any item in your car with e.g. a blanket, and an officer would not legally be able to move the blanket to see what's underneath without a warrant, probable cause to search, or permission from the vehicle owner (I'd add the caveat that seeing the shape of a gun underneath a blanket could probably pass for probable cause). So, moving that boundary from "the blanket" to "the window" to me seems pretty reasonable, except that a window tint doesn't completely obscure what's behind it like a blanket would. A tinted window fundamentally can't protect from plain view in the same way that non-transparent object can; the owner would be better off hanging curtains from inside the car.