I found this on the net;
https://www.beneficialdesigns.com/pr...hand-controls/
I don't know if this is something that could help out, or not?
It says it requires good dexterity, and arm strength.
The only other thing I could think of is a switch on the shifter (maybe activated by something like a motorcycle clutch handle) and an electric motor, and pump to assist a hydraulic clutch. Would require a bunch of fabrication to get it all working though. A rheostat could make it apply at a variable rate? Just trying to brainstorm something.