One alternative to either wing nuts or knurled thumbscrews would be a "coupling nut"- - - - -it's an all-threaded nut about an inch long that's usually used to join two sections of threaded rod together for various purposes. It will give those arthritic fingers something to hold onto while you're starting the nut onto the threads in a blind spot.

For example:

www.ebay.com/itm/305788928519?

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!