I've never seen an idea for an emergency rudder in a magazine or book that looks like it would usefully steer a sailboat except in benign conditions. Locker doors screwed to spinnaker poles are better than nothing, but they aren't going to take over in the conditions that you likely just lost your rudder in. Tow buckets in the gale?

I only see a complete replacement of the rudder you lost as a safety device that would make sense. Simply, adequate gudgeons through bolted on your stern and a robust pintle-ready 4" thick fir rudder below a settee cushion, ash tiller in the hanging locker. And that makes no sense, either, but the only emergency rudder that I can think of that would work.