Lots of big, old backhoes worked entirely with winches and cables. Look for Bucyrus-Erie, Ensley and Koehring. Interesting things to operate too! No hydraulics at all.
I am interested in this discussion also-
I don't need a backhoe for digging deep, but I could sure use a long arm with a "grabber" on the end to reach into blackberry clumps to drag out fistfulls with the tractor. I can use the bucket to position it, just want a winch mechanism (maybe electric) to close the fist, and a design idea for the fist.