Yeah I think I know what you mean -- something like this:
16x9 Hinged Masks that open to 2.35:1
If you decide to go that route, I'd be interested in seeing how you did it. With my limited space I'm not sure this method would be the best (nor would my sliding track method I described above). I may end up sticking with manual cloth/foamcore masks that I attach at the top of the frame.
Eventually I might just get an anamorphic lens and optically stretch 16x9 content to 2.35:1
