Have you considered a full face mask? Or a hybrid? The minute I told my specialist I sometimes sleep with my mouth open she put everything else away.

Sounds like you have your mask too tight and it will actually leak more when you do, there seems to be a sweet spot. The video talks about the right facial position and it took me awhile to intuitively find it. I probably wear mine a bit on the loose side and sometimes the hose will lift the opposit...