There was a time when we were first getting things together on the tandem that I rode almost exclusively with my hands right up against the stem. Once I got the feel for not using my upper body as levers to control the bike, I began resting them further out more and more of the time. If you're not controlling the bike with your hands, then there's really not much of a comfort issue; the hands just rest on the bars.

Bear in mind that, until very recently, we were riding 90 degrees out of phase, so any tendency I might have to rock the boat would have been exactly the opposite motion from what the captain would find natural, so the need for me to ride quietly was enhanced. Fortunately, I've always been much happier in the saddle on climbs and spinning a higher cadence than most other riders, so it wasn't a big learning curve to not wrestle the bars.

I strongly recommend that everyone ride rollers. I also think you should be targeting staying in the central 1-2 inches on the drum and try to do it with your hands towards the stem. Yes, I think the captain should do it too. We mostly confine our roller riding to December, when our roads are so filled with drunks and harried people that we choose to minimize our riding. We'll ride them for an hour or so as a warm-up for weights, which would be another soul-sucking activity but for the fact that I'm as immune to that as I am to ovarian cancer. My captain says I don't have to worry about brain damage either.