I think Shimano freehubs for tandems are 145, so it may fit, or thin the left spacer stack 5mm..
I don't own the tandem you have or a Shimano freehub, like that, but you can search the PDF online of them.
how about a Rohloff? 14 speed 36 hole (no dish), 135mm, * can be used with 2 regular cranks, same side drive, rather than the crossover type.
* maybe bond 2 2.5mm stainless steel washers inside the frame dropouts, notched like the dropouts ..
retrofit kit includes chain tensioner and torque reaction strut..
now several 3rd party offerings to shift it with out the grip shifter. on the bars..
...
Last edited by fietsbob; 12-29-17 at 12:36 PM.