I needed to do something to get some sleep, so the next day I developed a 'fix' to prevent mouth breathing while using the full face mask. And, IT WORKED!
My 'fix' was to fabricate an obstruction that rested between my teeth and the inside of my lips, thus stopping mouth breathing in its tracks. I used a piece of plastic, removed from a disposable tray that a hospital meal was served in. I made it much larger than it had to be in order to negate the chance that it might become dislodged during my sleep and choke me. The plastic sheet was thick and rigid enough so it wouldn't deform if I did indeed try to swallow it during my sleep.
While I am not sure if it was as safe as it could have been (with more proper/thorough design), it did get me through the next 2 nights in the hospital with satisfactory sleep. While I can't recommend it for everyday use, the information might be useful to others if they get stuck away from home in a similar situation.
I am reminded of this due to my present situation, which is trying to figure out whether my Large Leak is caused by the CPAP pressure forcing some amount of leakage past my lips as I sleep. So, I'm tempted to try it on myself tonight.
I am curious whether safer (commercial) mouth breathing blockers based on the same concept are available though.
Any ideas?