Traditional foglights draw a fair amount of current and unless the wiring is already run from a relay up under the dash it might be worthwhile considering fitting a relay and picking up power from a main powered line rather than through the foglights switch.
I guess this could be avoided if the foglights themselves or the bulbs are low current LEDs.
On my car I have the front foglights set up as driving lights and the relays are set so that they can only come on when the headlights are on high beam. I had this set up after discovering that I was sometimes inadvertently blinding oncoming drivers

I did consider using the old trick of having one foglight and one driving light but my experience of front fog lights is that you tend to get too much light reflected back at you from the mist so I thought just having driving lights was a better idea.
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