Once you're able to hold the support press for 20 seconds, you can begin the transition to practicing with your top hand positioned directly above your bottom hand.
As the leverage here becomes significantly more difficult, we'll be elevating the hips above the shoulders and bending both legs to compensate. Changing the angle and shortening the length of your body will allow you to get a feel for holding yourself sideways against a vertical pole without having to overcome your entire body weight.