Don’t know where you live, but when you get the chance on a decent weekend, borrow or rent a road tandem from a local dealer for a weekend and ride it.
We started tandeming in ’06 and what made it work for my wife / stoker was her confidence in me as an experienced rider. She may not have a lot of confidence in other things I do, but she knew I could handle a bike and that she could completely trust me to handle a tandem with her on it. With your biking background, you have that to offer also. If she can feel rock solid on the bike, in the pedals, at all times, you should be good to go. It will be much more work for you, but it will be worth it. You’re going to have to carry the load sometimes, as she will not be able to keep hammering with you until she gets her biking muscles and stamina. But, as we say, that’s life in the Big Ten. Great training for your single rides.
When I met my wife two years ago, she was riding a 40lb cheap cross bike on local paved trails. She was not too keen on riding the roads, in traffic. Now she has a very nice roadie and a new lightweight urban setup for errands. Sometimes she says, “naah, let’s leave the tandem home and take the singles.” (She lets the dog out and runs with him a bit.) Very cool.
Also, if you like tandeming, get the Tandem-Com intercom for more and better communication while you ride. We won’t leave home without it.