If I understand your setup correctly, have you considered a tray? . . . such as the Secraft with an extendible mount? Here it is with a Cendence and a 12.9" iPad. I used it originally with a standard
Inspire 2 controller as well. The Cendence fits with a small adaptor kit that just has 3 or 4 parts. It definitely holds the iPad securely. I even leave the leatherette cover on it, just folded back. The tray with back/shoulder strap also helps holding the weight of both units. I hope this helps, AerialPerceptions!