I have two 14$ o'reilly chinese daylighter knockoffs that I installed 24 volt H3 bulbs in, and sprayed OD green. Twice as bright as high beams, effective on the beach. Wired them directly to the battery with a inline fuse and high amperage military style switch. The easiest way to run the ground is to attach the wire to lamps bolt when you install it, that way you just have one wire to deal with.
Also, just use a probe to find a hot wire for the front parking lights while you have the parking lights switched on. Then probe and find a wire for the rear running lights while the headlights are on. Connect the rear running lights to the front parking lights, and you're good to go.