I think a tiller is better up to somewhere around 30 feet. So I agree with your concept.
But our tiller post comes up over the level of our cockpit seating. With some rise in the tiller shape, that means the tiller is over the knees of the helmsman/woman, and of others seated in the cockpit. Emergency tiller posts tend to end close to the cockpit deck - not very convenient for steering through a couple of hours or more. If your emergency tiller does not rise to your knee level, you will have to design a strong and reliable extension that will connect securely to the head of the emergency tiller. Certainly doable, but not an easy thing to design or fabricate, I guess.