I'm starting to put together my ideas in preparation for a 4x5 monorail for field use. As part of this, I thought it may be better to use acrylic to cut down on weight however I've never seen anyone mention or do this. Is there any reason it wont work? Also, I forget right at the moment, is the film plane in the same position as the front (lens side) or back (viewing side) of the ground glass? - i.e. what surface needs to be in the same position? Thanks.