Just a thought, but how about using a regular large window with a script change from Texture to Alt Texture when the player hits the switch? Borrow the 'blinds down' texture from the fake window, then use a script to switch to Alt Texture, which will be the regular see-though window texture.
Alternately, if you wanted to be really fancy, you could make a decal of the shutter rising, then position the decal over a regular window and trigger it to play once when the player hits the switch. That might be overdoing it a bit though