I have Graphlex Speed Graphic 4x5. I wanted to purchase one of the lomographic backs, to shoot Instax wide instant film. Is it possible to add a second set of infinity stops to the rails and set them to infinity focus for the new back (plane of focus is different)? My plan is to install the stops and set the infinity focus for the back and If I shoot standard film, I can use the original stops. What about the accuracy of the rangefinder, will it be unchanged? Any inputs appreciated. Thanks.