Enlarger focusing knob extension

If you want cheap cheap then:
just get the inner tube from a small bicycle tyre and hang it over the existing knob. It will grip becasue its rubber and you can just grab the bottom of it and pull it either way. Or a flat rubber belt.

But I still think a wide angle lens and tall focus finder would be the best solution.

Or a electrical motor geared to the focusing shaft. (Kaiser used such in their autofocus set-up.)

Or just get a Magna-sight
(and then stand up and tilt your head up so that you can see through the bottom of your glasses)

or get some platform shoes if you're vertically challenged.