According to this article, other than Gus, Ezra, and Phineas, ghosts really do hitchhike outside of Disney property!
"In 1965, May Doria from Oklahoma decided to visit her sister, who lived 60 kilometers from her. ?I was driving along the highway, and when I passed by a school building, I saw a boy. The boy was standing next to a roadside; he was hitchhiking. He looked like he was eleven years old. I felt sorry for him: he was standing by the road alone, without a jacket, and it was pretty chilly that evening. I stopped near him, opened the door of my car, and then offered him a ride. He sat next to me. We were driving and chatting about stupid things that strangers usually talk about. He was a good boy; he had very nice way of talking, and there was no slang in his speech. We were driving to my sister-s town. All of a sudden, he asked me to stop the car and let him out. I looked around, but there were no houses nearby. I asked him, ?Where do you live?¦ He pointed out his finger and said, ?Over there.¦ I looked in the direction that he was pointing, but there were no houses over there either. Then I turned my head back to him, but he was gone. He disappeared, as if I was driving alone the whole time! I stopped the car, got out, and started looking for him, but he was just gone. I was completely shocked.¦
Two years later, May learnt from other people that drivers found themselves in similar situations quiet often in that area. The first time the hitchhiking ghost-boy appeared was in 1936. An elderly man said to May: ?He is a good ghost. He does not bring harm to anyone."