Reviewing the comments here, not sure why these tours would be so popular. Unless your Dad has a strong constitution and money to burn, not really worth it and not very interesting, IMHO. A horse is a horse, wild or not. Seen plenty, in bridles and in paddocks. Not sure what the big deal is.
Did not understand when we went on the tour the intrusions on private privacy as the hummer wandered around on what seemed to be occupied private property. Felt like we were voyeurs.
Glad we did it, I guess, but many better ways to spend your time, and especially your money, on OBX. Not recommending it to our 2019 guests. Guests a few years ago thought tours of Assateague horses in Maryland was much more informative and useful, and where our guests camped out on the beach. OBX tour seemed like a tad too commercial and overdone. Hummer recommendation at the end was TripAdvisor plugs for the guide, tips, and for Black Pelican restaurant. Maybe a bit too horsey. One of my less enjoyable experiences on OBX. A pass IMHO if you have other options.