I think the important distinction is the side effects of having a neighbor that rents out on AirBnB. In your case it's "occasionally his guests encroach on our driveway which is adjacent to his" which I think is unacceptable. I have rented ~10 AirBnB's with friends over the years and in every case we either flew into the location and used Uber/Lyft to get around or carpooled there resulting in us only using the allowed number of parking spaces.

A family or group of people occupying a residence that would be occupied by a similarly size group is not a problem in my mind. It's only when there is noise at all hours, trash left around the property or on yours, or parking in your parking area that I would really start to mind.

Maybe that's easy for me to say as someone who doesn't (that I know of) live near someone who rents out on AirBnB. That said, I do live next to 1 house that has ~6 (I honestly can't be sure) people that live there (all adults) and on the other side have a house that is often vacant and the owners have their parents live there sometimes I think and none of that bothers me. That's mainly because they keep to themselves, don't make lots of noise, leave trash laying around, or take up extra parking. So knowing all that I don't think I'd mind an AirBnB as long as all those factors didn't change.