I built a lot of motion control systems back in the day for instruments that make most sailboats seem cheap. Movement overtuns were not an option. Fortunately it is easy to implement limit switches into pretty much any control system. Personally I don't understand why autopilot installs don't include limit switches on the rudder that stop motion when they are hit. The only problem I see is that on a rudder with hydraulic motion actuators, the dynamic loading of the rudder makes simply stopping the pump at a limit inadequate since if the load decreases residual pressure in the cylinder will move the rudder farther. Of course a simpler way would be to customize the hydraulic drive to the boat so that the full range of hydraulic ram movement corresponds to the maximum desired rudder movement. Of course that would cost money so few boat owners would be willing to pay for it