Is there some reason why a partial oral breathing tube could not be used to treat sleep apnea? A full oral breathing tube goes way the heck down the trachea and has a balloon on the end to keep it in place. Since apnea closes off the area at the back of the mouth, one might think that a much shorter tube, just long enough to get past the the back of the tongue/soft palate might provide enough of an airway - without having to thread a tube so far down. I imagine that the position of the tube in the mouth might need to have its position fixed by clamping it to the teeth (as with retainers) or possibly by holding it to the front of the mouth with a band that goes around the neck, but that wouldn't even be as bad as a CPAP mask, where one must also deal with the tube.
My sleep apnea isn't too bad, it only manifests if I sleep on my back or sitting up. So I sleep on my side, but it would be nice to be able to sleep on my back. The side effects of the treatments I have tried so far were a heck of a lot worse than the problem. CPAP pumped so much air into my guts that my abdomen felt like a basketball each morning. The mouth appliance did awful things to my jaw joint, so that I couldn't shut my mouth normally for 90 minutes after waking up. Plus when in place it felt like somebody was standing on my front teeth, which wasn't very conducive to sleep. No way I'm going for a tracheotomy, and the other surgical interventions seem to be better on average for the Drs wallet than the patients' symptoms.