Hi Mike!
A little clarification, please. Does your tandem have a derailleur drivetrain with eccentric BB for the crossover drive, or is it a Rohloff drivetrain with eccentric?
On my derailleur tandem with crossover drive, I find the timing chain lasts a very long time thanks in part to running 40t timing chainrings. When the chain stretches within wear limits, I simply take it up using the eccentric, being mindful to replace the chain before it stretches far enough to exceed wear specs. This means I never reach a point where I would need to actually remove a link. I treat the drive side as I would a single bike's derailleur drivetrain, replacing the chain as it approaches its wear limit.
If your tandem has a Rohloff drivetrain, then yes, you should be able to remove a link-pair and dial-back the eccentric to extend chain life, sometimes to an astonishing degree, as the chain and 'rings can wear-in (and wear out!) together and still mesh smoothly as a set, unlike with a derailleur drivetrain. Continuously feeding in new chains as they approach their wear limits will extend the life of the chainring and cog, but may not pencil out in the end when multiple chain replacement costs are weighed against eventual replacement of the whole works (chainring, cog, and chain to start the process anew). Don't forget the chainring and cog on Rohloff drivetrains can be reversed for additional service life.
Best,
Dan.
