Oby, another idea. just make a fixed rudder. one lopro one piece of pipe about 18 inches long and one triangular piece of aluminum. Fix it to the back of your cat frame where it can rotate upwards if you would happen to hit a rock with it, don't overtighten the lopro and it will just swing up. Don't have a picture, mine is at fishing camp. But they make a cat track great with a motor or oars. If you don't have a way to weld alum it could be bolted to the pipe. once you deploy it for the first time it might need a little tweaking to get it correct. This can be done by bending it or sliding it across the yoke.
If you start off asking for help, you probably should not even start off.