I'll stick w/hydraulic actuation of one sort or another. That's the 'best' thing IMHO to get from "A" to "B". Rigging up a mechanical linkage would be a chore compared to running a hydraulic line.
That said, if there were a way to bleed/refill the M/C w/it under the tank, I wouldn't let the 12" push rod bother me- one could be made that would have basically no deflection. Would there be room for a remote reservoir lid on the existing M/C if it were mounted under the tank?