What's the best place for the power source for the switch?
Thanks in advance!
Battery. I use Bat .terminal of wire loom.
I mount a little 4 fuse holder next to the battery. Run a 20 amp fusible link from the battery to the fuse holder buss bar. The power for anything (headlamps, brake light) comes from one of the four fuses. I have a 7 1/2 amp fuse on the brake lamp circuit.