Yvonne, you can run pigs with horses. I had two barrows (gelded boars) with my horses and they got along great except when they stole the sweet feed. LOL They need a tighter fence than a horse as they will lift the bottom. It will create a wallow. The Mazuri feed is great and don't feed ag hog food as it's designed for bringing hogs to market size fast. You'll find they are very intelligent and fascinating animals. Did the vet detusk him ? If not free ranging with horse will help keep the tusks down. Word of warning though, being omnivours and smart ones, keep away from torts.
No offense but I could honestly think of a dozen or so animals with cuter butts myself, but beauty is in the eye of the beholder, I do think he looks a little slimmer.