How about using a stiff, oversize, conduit AROUND the power cable - also protecting it somewhat from wind bending, sunlight, and such - as the furling pull?
Let it yaw with the head, in a guide near the bottom to keep it roughly centered, and counterweight it at the top to keep it from rubbing up and down on the cable as the mill auto-furls.
Grab it and yank, and hang a weight on it to keep it down, when you want to furl the mill. (Or perhaps arrange it so you just take a weight OFF it to furl and put on ON it to unfurl. But I prefer the postive yank to furl, since you can yank extra hard if the pivots/guides/whatever are a bit sticky.)