Has your stoker had a professional fitting? This can make all the difference. Even one cm up or down can make a world of difference. We also have a new C'Dale road tandem, and my LBS helped me configure a better handle bar arrangement for my stoker, getting the bars up as much as 3" or so, but maintaining total adjustability. In an earlier thread, woodcycl shows a photo of what we've done. Go here to see what I mean...
http://www.bikeforums.net/showthread.php?t=133461