I have read most of this one and think if we combine both Ideas it will work.
1) Alternator that can be switched on and off. Many one wire alternators out there or learn how to turn yours off and on.
2) when brake light is on make the alternator. Use the power robbing alternator only when you are slowing the vehicle. Kinda Like regenerative braking on electric vehicle. Maybe even upgrade to a more powerful alternator so you will charge enough during stops.
3) Put in Led's and solar panels just to be cool!
4) Stop buying gas and build a electric
Larry
http://fiero-ev.blogspot.com/