Hm... I see. I would release my rig, but I have some permission problems. My rig contains some mesh parts from other figures which are not allowed for redistribution. And in your misfortune this includes the tongue and the teeth^^. I will recreate them to avoid these problems but I'm short of time now. In the past I planned to release my rig. But two rigs of the same character and the same base mesh for the same application. I think this is not really a good idea.
The rig from Extend3D has a MouthOpen morph^^