OK, you seem to have some Mickey Mouse aftermarket wiring harness that doesn't follow the factory wiring diagram, so I have no idea where the headlight switch power is coming from. The headlight circuit should be powered from a source of battery voltage that is not routed through any type of fuse so there's no way for the lights to lose power for more than a few seconds. That's the reason to use a self-resetting circuit breaker instead of a fuse. Since you've got a voltmeter instead of the original ammeter, the original circuit diagram can't be followed. Far too many people have bought into the fairy tale that ammeters are some kind of fire hazard. This thread is getting far beyond something that can be solved without some hands-on work by someone who fully understands DC electrical systems, and can trace the individual circuits you have.
Jerry
