RE: What wire for LED headlights
There was also the type of wire used in the old record players, very fine and thin, to run out to the tonarm, and had to be light and flexible so no force was added to resist the tonearm following the groove, but can't find the reference to it, i.e. specific name.
There's other tricks, which you may not need, like live steamers often run a single wire, and use the metal chassis as a ground.
On the LEDs, recently I've used some flat topped LEDs for marker lights, which spread the beam out a bit more.... they are often used in outdoor christmas lights, but they are appearing more and more on the aftermarket in 3m size.