So far I've use natural light from the windows, outdoor light, and house lighting with an additional clamp on light near the machine.
At one time I thought about hooking up a bicycle generator system with a battery like your neighbor did to the treadle, but never have gotten around to it.
I can't really tell how much extra effort it would take to treadle the machine before I'd try it. But I'll bet it does add some considering how it made pedaling my bikes a lot harder.
Joe