Have you thought about servo pendulum wind vane steering? No electronics to
bugger up and no power consumption. Plenty of second hand Aries/Hasler
vanes(and others) on the market that can be refurbished cheaply and will
provide effortless steering in conditions that would make a tiller pilot
pack it in. You could also add a small tiller pilot to the vane to make it
more efficient in holding a steady course or for use in lighter conditions.

FWIW

Andrew