This isn’t a good replacement for a strict press, since the instability makes it so you won’t be able to use as much weight. It is, however, excellent training for the muscles that stabilize your shoulders during a press, including your core—basically everything from the hips up. Make it harder by using thinner bands, even if it means you need to double them up to keep the weights from dragging on the ground. You aren’t limited to plates for this one, by the way; kettlebells work well, too. For an extra challenge, use a weight that is easy to press and then walk around (or march in place) while holding it overhead.