Dave provided me with some valuable advice when I built my bino. My image merging mechanism is similar to the one on the smaller solid-tube bino he has documented on his site. It is pretty basic, & what Chris is doing is altogether more sophisticated.
The tailor-build idea would make life much simpler. Aside from the sharing issue, I can see some interesting challenges arising if you should ever sell it (when you build a bigger one, naturally). I can imagine an IIS listing along the lines of "pristine bino with superb optics, only available to purchasers with eyes spaced 64.5mm apart".
Phil