Brice, thereís nothing wrong with your diagram with the exception of running the power feed to the switch from the battery and using the same fuse. The reason I say this is because the idea in laying out an electrical circuit is to minimize the amount of wiring and also not to depend on a higher rated fuse to control a lower rated branch circuit, i.e., the switch in this case. In your diagram you'll also have to run two sections of wire thru the firewall, one coming from the battery to the switch and one going back to the control relay in the engine compartment. Other than that it is functional.
As for Matthews diagram, its functional, but again your having to run two sections of wire, one to feed the switch and a return line to the lights. Also, your running the full current for the lights thru a much longer section of wiring that could cause resistance and heat depending on the gauge of the wiring and any connections especially at the switch if there simply push on spades. One other thought is if you ever need to replace that switch and forgot about its amp rating and put a lower rated switch in you could wind up with a smoldering dash or even fire before the fuse would blow.
As for a power source to feed the switch any tap to 12 volts with sufficient current rating from inside the cab is fine since this is a low current feed. The coil in the relay only draws 14.5V @ .16 amps. Fusing this circuit with a 3 amp fuse is more than sufficient. The only question here is do you want the lights to work with or without the ignition on. If you notice in the KC diagram the feed shows high/low Ign. The reason is because some States require Aux lights to be wired so they can only be turned on when the high beams are on. As far as off road lights go some States say you must keep them covered while driving on road. As far as forgetting to turn them off well Iím not saying it cant happen because it does, but you should only be using them at night so it would be a little hard to forget especially if the switch is lighted. Bottom line is itís your choice with this one. I personally wired mine to the cigarette lighter power feed for the light switch since its mounted right next to it. Again keep it simple and short. With this setup I only had to run one wire to the engine compartment.
As far as running two relays, one for each light, I see nothing wrong with this setup either, other than thereís one more thing that could go wrong...Murphyís law. Even running two 130 watt lamps the current is only going to be 17.95 amps @ 14.5V. Well within the rating of the relay at 30-40 amps.
For the power feed to the lights you can either take it from the battery or the Battery junction box depending on where you mount the relay. Just make sure you put an inline fuse as close to the tap as possible.
Remember, the idea is to keep it simple, run as little wire as needed (especially thru the firewall), and match the wiring, relay, and fuses to the current load.
Just my two cents...