The bungee would assist by countering the clutch springs, but I don't know what it would do mechanically to the clutch as it would be like riding the clutch all of the time. Adjusting the lever to bring it closer to the grip using the built-in adjuster and adjusting your hand position further back on the grip will give you more mechanical advantage. Any re-work of the master cylinder or lever arm for it would result in a much longer throw to release, and probably hurt more. Wear a brace while riding to force your wrist into a position that does not hurt and perhaps an elastic brace for some support would aid in comfort. The controls can be moved to the right side by specialists that deal in mobility and accessibility issues if you feel this will be a permanent issue. I suspect that your biggest problem will be while setting at a light, not while shifting. Holding it all the way back at the end will ease some of the pressure. Maybe a quick-release holder could be fashioned?
He would have a lot more problems than just a heavy clutch.You might have to trade the wing for a new VFR until Honda puts a dual clutch on the wing. It's got to happen and when it does, it will be the single most significant improvement to the bike since it was built.