I would think that you will be OK using the stock fog light harness and circuit. You can check the fuse for that circuit, and then multiply the fuse amp rating times 14.4 volts supply to determine the maximum wattage that will be allowed by the existing circuit. The stock harness wiring itself will allow significantly more amps than the fuse rating.
I had a somewhat similar situation with my backup lights, in that even after changing to direct replacement in-socket LEDs, the enhanced light from the LED backup lights was not sufficient for me to easily navigate my driveway in reverse, with stone walls on either side, at night. I decided to add two Rough Country 8" LED light bars under the rear bumper.
In this specific case, I was advised that the backup light circuit (which requires far less power than the front fog lights) was marginal in available power to also run the two 8" LED bars, and a new direct wire to the battery was run to power the two 8" LED light bars, along with a relay that is activated by the original backup lights circuit to turn on the two 8" LED light bars.