I bring a wedge with my everywhere I go now to tilt my pelvis and stacksit. I still find sometimes that I want to use the backrest of the chair. I realize the principle of this technique is a balance that allows your spine to support itself without muscle intervention. But is it okay to position in such a way the integrity of the stack is intact, but the back of a chair provides a slight upper back support in the technique?
As much as I'm sold on stack sitting I think we still have have an urge to sit back.