Once upon a time, I was looking for Tyvek that didn't have printing on it. I tried small squares cut between prints and it was hard to work with. There is lots of painted glass in use for shoji, but it looks like painted glass. Good quality shoji-like glass is available. Check out your local Japanese restaurants. If you don't find it and want it, let me know and I will inquire.
There is a shoji panel in the closet beside me that is made of common copier paper - you would have to see it to believe it. Poly-based plastics have too much stretch, but hard plastics can work. I have used 3/16 white polycarbonate for footlights in Kumamoto En and have been happy. Perhaps too thick for your application.
Why will it be so exposed? No overhangs or is it from strong winds? If it is high exposure, your wood will need special treatment anyway.