There's another relevant point regarding OB. It wouldn't be an illegal stance if you played from out on that small wall if it was considered inbounds even if your feet were hanging over the OB water on each side. You can't be touching OB when releasing the disc but that doesn't extend to the air above OB. When you're releasing a shot maybe near an OB sidewalk, we've all probably swung a hand or foot over OB during our throwing motion and that's allowed.
Rater of the Tossed Arc