I just run a regular BB-mounted kickstand on my tandem. It's far enough back along the axis between the steering head and the rear tyre contact patch to not be destabilised when the handlebars turn sideways. Also it has worked quite well to hold the tandem with loaded panniers on it.
Normally I use a rear stay-mounted kickstand on my single bikes, but the tandem has the drum brake reaction arm mount in the way.