I would say forget the old stick on window tint. There is a new technology that has surpassed the old window tinting ways and it is spray on window tinting.
You do it yourself and should be able to make it as light or as dark as you want it. I have seen some things that were sprayed with it and they looked excellent.
I would be worried that the sticker tint would begin to peel in a marine enviroment. I am planning on using this stuff on my South Coast 22 project boat some time soon.
You can get this one at summitracing.com and search tint at the top in the search box. There are other spray tints out there too.