you don't need the alternator. Put a solenoid switch in. It is cheap and you don't have to get a big switch for the large amp draw. One battery is fine. ignition doesn't draw much to run the engine. I also bought a $8 ignition switch from the auto parts store. Makes it easy to wire up and a set of cheap mechanical gauges. I did wire my alt. to pretest my wiring for the charging system but you don't have to.
