"You may fabricate a voltage regulator & cut out but you still need a current limitor"
Have you ever heard about the trick of using a twelve volt bulb (like an 1156 or something) between field and ground as a "redneck regulator?" The bulb resistance acts to limit current in the field, which gives you a steady output from the generator. With the right bulb, you can get a very good match for the electrical load of your vehicle.
I had to use that trick on my last trip to Vermont when my bike stopped charging.
