I rode mtb. tandem with hubby before I started riding single. He's 11 inches taller and about 100 lbs heavier than me. I love tandem riding, I love being the stoker and because of the size difference, will never be the captain. After we did some jumps on the tandem, I decided I had to try a single bike (so glad, can't imagine life without mtb. riding on single).

Communication takes time, it also helps if the captain tries stoking for awhile (they get a first hand look at the importance of communicating everything, even if it seems ridiculous at first).