While I despise when others use this phrase, I guess it’s ok when I say to myself: “Google is my friend”.
I found this guidance online, which clearly says the human p-word is indeed a solution, so to speak:
How Should You Use Human Urine To Repel Skunks?
I think you already know the answer to this one, and you probably know what I’m going to say here.
Well, go outside and pee. Some scholars say you need to or could dilute the mixture, but I don’t think we need to overthink this.
Depending on where you live has a factor to this and the area you’re trying to protect.
Essentially, it would help if you thought of this as “marking your territory” the same way that a dog or other animal does. Does Human Urine Repel Skunks? - Pest Pointers
Might be a workable remedy if this were a one-time thing. But apparently, you have to do it often. I will mercifully end this paragraph right here 
Other suggestions are coyote urine, or as you suggested, fox urine. The problem is that, where we live, there have been coyote and fox sightings, and I’m thinking this might attract these critters to our place. I guess, in the scheme of things, that a skunk tangling with our pupper is more desirable than a fox or coyote doing so. But great suggestions anyway.
Wll try the ultrasonic devices and perhaps, on occasion, more “covert” measures, Worst case, I suppose we can peacefully co-exist with our skunk neighbors. After all, I guess we’re squatting on their land rather than vice-versa.
Since this is probably the only time I will ever use this emoji, I might as well go out all skunks blazing! 
