Thank you all for the responses.
I've been reading a lot about this today and think I may have found my solution. Since I will have windvane self-steering anyway, there appears to be an emergency rudder attachment that you can get with the windvane gear, so that will probably be my first backup/spare. I'm struck by the incredibly fat/piggish bloat of a price for the thing though and will have to close my eyes when I place that order for sure. In fact I'll pay for the windvane self-steering, but I might figure out how the emergency rudder works and have something fabricated instead of buying that part of it. There is such a thing as too expensive.