Running the headlight ground wires back to the engine or frame makes more sense than relying on the splash shield to provide the ground, or at least add a ground wire from the splash shield to the frame on both sides. No telling how mush rust that current is trying to bridge on its way back to the battery. I'm also a fan of using relays to carry the headlight current and letting the dimmer switch trigger the relays only.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!