A lot of people don't know this, but the first generation of Goldwings from 75-77 came with a backup kick starter lever that went into a mechanism at the back of the engine and transmission to turn the motor over using the starter clutch one way bearing on the flywheel, which was offset to the left of the crankshaft. The starter used a chain to spin the same mechanism and a simple one way ratcheting pawl gear was used to engage when the lever was pushed down. Something similar could be employed and mounted directly to the pulley, or indirectly with a chain and sprocket system. All it needs is the ability to freewheel when the engine is driving.