I'm finishing a nice light touring & travel bike -- 650 B, S & S couplers, Rohloff Speedhub -- that will be belt-driven, and I'm perplexed about the best crank solution. Rohloff's chain line is wide -- 54.7. Gates makes an Alfine-specific crank set (S-300, I put one on another belt drive recently), but I think the Alfine chain line is only 46 or 47 (depending on where you find the docs). I could turn some spacers on the lathe and set the cog off a bit, but 8mm is a lot for that. Use the outer mount on a square taper triple? Has to be 104 four arm or 130 five arm BCD. I could make up the dif with a wider spindle? MTB cranks?

Any help gratefully received.