I would suggest using a fuse-linked 10 gauge wire to supply the power to the headlight relays, and fuse the headlight switch with a 10 amp circuit or so, just enough to carry the trigger signal for the relay coils. That will eliminate one heavy current draw circuit under the dash. The dimmer switch will also be spared the load of carrying full headlight current that way, as it will become part of the relay energizing circuit. If you use a voltmeter instead of an ammeter, that's another heavy current circuit that's eliminated, although I consider that modification to be foolish and unnecessary when a simple shunt at the ammeter accomplishes the same result.
Jerry

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