HAHA! Rube Goldberg. The heading input from your engine, pops a balloon, which triggers a small wind up toy to walk across your deck, knocking a broom handle, which turn the wheel at your helm.. Works for me!
Why don't they build a Auto Pilot, using only a Flux reference input mounted on the outboard? A simple auto-learn mode and a GPS and you program the boat (in a setup mode), then you set a course either by degree, or via GPS input. The position of the engine, vs the postion of the boat would determine your heading.. However, if it was based off of a flux reference unit, which will always keep the heading of the boat in one position, regardless of the GPS limitations of speed, it will always reference magnetic posion and GPS location in relation to the bow and/or stern of your craft and the position of the outboard as a separate unit. If you are going at speeds below 1kt, the GPS reference would only have to kick in every 5 seconds to keep you on track. You could even put in mechanical stops (instead of rudder reference) and if the max distance of your engine's steering was exceeded and you were loosing your course, it would then kick the AP off and even trigger an alarm. I really don't know why they need the rudder reference unit. Maybe in the old days, they needed it because of lack of modern electronics.
Trolling for salmon here on the N. Coast is near impossible above speeds of 1.5 kts and even harder if you are stuck at the wheel. Magnetic reference is best. Why not mount one on an outboard?
Ok, I'm officially a geek.