This is the usual set-up for a digital puppetry implementation. We have two guys inside the booth. The first is the main puppeteer and the second guy is the tech assistant.
Yes, a single puppeteer can handle the performance but in our experience you really need a second person to handle things that unexpectedly happen. In a live performance, the puppeteer can’t just go out and fix a loose video cable.
You can also see the reason why we use manual mouth controls. i.e. We don’t use microphone control or even a face cam setup. Those things look cool, but are not reliable in a real performance scenario. The booth we’re using here is just a cloth booth for hiding the performers. During our first attempts we tried to use a sound controlled puppet but there really was no practical way to get a sound free environment. So in conclusion: the best way to control a puppet;s mouth is to still use the puppeteer’s hands.