That sounds like a neat design, I would suppose rails could be added to the rear for the extension, that would avoid the entire front rack and pinion and the problem of eventual wear and slop that occurs, plus it simplifies the cost and design some too. Do you think it is a good design for an 11x14 these days? Are you going to make several extension rails for different focal ranges, that way you won't have a rail poking you in the chest when it's not necessary. It sounds like you have geared movements on all of the camera movements, was that for ease of use?