I have a Shimano M900 triple crankset (last square-taper XTR crank), which I've used on road bikes since 1995 (built my first road bike with a triple while working at a shop during high school).
I've always used it with a 103mm bottom bracket, but ideally I'd have something 95-97mm, for proper road chainline and narrower q-factor.

The problem: nobody makes a square-taper BB narrower than 103mm, except for Phil Wood's 92mm (which is too narrow).
Am I missing any options here, or should I just accept that 103mm is the best I can do?