With a little dedicated tinkering it would probably be possible to convert a single-acting air brake chamber into a vacuum assist for the clutch linkage so just a small amount of pressure on a hand lever would be needed to operate the clutch. Chevy cars had a similar vacuum assist setup on their column shifted 3 speeds in the late 1940's. Gears could be changed with nothing but fingertip pressure.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!