We got to ride with another tandem couple this past Sunday. The Stoker (respect for the Stoker makes me want to capitalize the first letter), suggested that my daughters position on the bike was wrong, that she should be more upright and the bars should be higher. My daughter all of seventeen whispered and asked me what she could be talking about. I suggested that perhaps the difference in age and flexibility was why she said those things. After our exchange, we politely told her that her riding position on the tandem was exactly the same as on her single bike and that there was no need to change it. Just goes to show, that everyone has a way to fit you on a bike and no one single way works for everyone. There is just more than one way to skin this cat.
BTW, the way her fit position was determined was on a Compu-Trainer with a coach, where things were adjusted first for comfort (I actually had her very close without the coach) and then small adjustments were made over several sessions to maximize power.