Hey Ditchmiester! I saw your post here and wanted to clear up some points.
How important is it for the vinyl to be "optically clear?"
The reason I ask is because typically a manufacturer won't list their material as "optically clear" unless it meets whatever tests they have for determining that level of optical clarity. And normally the only vinyl to recieve the "optically clear" label is going to be cast.
That being said, there are plenty of calendered vinyls which are very clear; they just won't have the "optically clear" tag on them.