Is it possible for a face it self to not be rendered? or only be visible when normals are pointing towards the camera?
Like in the winosi comarison gallery. two of the faces dont directly appear (front and side), but still interact with the light ( ie, colour bleeding ) and show up in reflections.
http://www.winosi.onlinehome.de/Gallery_t14_01.htm
This would really help for small interior scenes, where ripping the mesh would disturb the lighting.