I woke up rejuvenated to try messing with the onion hidden service again.

Instead of link-local addressing, I set up a dhcp server on the tor host for only the hidden service interface, serving a fixed ipv4 address.

Switching to DHCP and IPv4 fixed 90% of the problems.

I now have only one problem left, that the host machine still needs a static address. It won't autoconfigure, still.