I wouldn't worry too much. Disney rides are generally accommodating to larger people. My friend, who is a big guy, once got on RnRC and the restraint literally clicked once. That was as far as it could come down on his big shoulders. Teh CM checked it, said it would be fine. My buddy was scared but he was indeed fine. I think Seven Dwarfs Mine Train was the most constraining for him and he de-boarded beforehand. He also could not do Flight of Passage. In some cases, it was certainly possible for him to ride, however it wasn't very comfortable for him, so he tended to shy away from repeat rides. Space Mountain was one where he did that and it had a lot to do with leg room.