Well slew foot is surely on to something IF you want to stay 6 volts. And i do think that using the electronics that came originally but using a few tricks to get to some LEDs is not a bad idea. I'm using hpi minis in all three of my hobbits builds and in my magnum. The amount of available juice to run things is impressive. So yes if u r going hpi or a few other 12 v lighting systems plus a cdi , I would float the light as I illustrated , run it to a two wire volt regulator and then to a silicon bridge or go the trail tech 5 wire with a battery to act as an electron sink.
Both allow you to utilize the original harness with some modification.