The high beam low beam mod can actually be enhanced in this fashion for maximum reliability.
I have used the APC wiring loom, but I wasn't impressed with the relays (not true, I thought they were junk). So when one failed I replaced both with continuous duty solenoids (they look like the old Ford starter solenoid...don't use them!) requiring you to cut off the molded plugs from the APC kit and use solderless connections. The connections are obvious, I can elaborate if need be.
The sweet part was thinking about the Painless kit for Chevy trucks to illuminate high and low beams and realizing a simple diode would make it happen. So with both continuous duty solenoids mounted above each other I connected the solenoids with the diode inserted and all four headlights were on, or in this situation it would be both filaments in a single bulb.
The continuous duty solenoids are hell for tough as they are used for switches in golf carts (36 volts) and as Chrysler glow plug relays. You must use ones that are rated for continuous use, and I can't think of a system you could protect with them that would ever fail. Plus you can use tiny trigger wires to activate and huge wires to your accessory.