Roger all that!
While the two problems may be complementary, the could possibly be just coincident. Or, if they are only coincident, but also one exacerbates the other, you're no further ahead...and you need help with both, thanks very much!
I think you should deal with a neurologist who can at least validate your OMD, but you also need a polysomnography, or if that is already done, and verifies your UARS, you need PAP therapy that can help.
When I first started learning about my own severe OSA (obstructive sleep apnea), and people on line were complaining about dry mouth, mouth breathing, and not feeling better after what the machine claims was sufficient hours of use (but not necessarily of useful therapy), the coaches told us to learn to place our tongues at the roofs of our mouths and to leave it there, practicing often during the day until it became the tongue's go-to position. Didn't work for me, and the result is that I tape over my mouth with the mask on. But...you're already there! Maybe your version of it is overdone, though, and actually is intrusive. Hard for me to figure this out.
I feel for you. Being housebound is bad enough, but bedbound? Yeesh...!
You may need to avail yourself of a sleep clinic to learn how to isolate your throat and tongue, but only with your brain doing it, like ignoring it, and then try to sleep normally with the proper PAP setup.
It might be worth a shot for you to spend some time at apneaboard.com forum. It's a free site, safe, tons of gurus there, and someone might know of someone, or you'll get an actual patient, who has some familiarity with your circumstances and can offer some help. I am there, have been for about seven years now. At the top black marquee, top of the page, you'll see 'OSCAR', which is a freeware diagnostic app you can download and poll your PAP machine for some really good info that most patients don't know anything about...even that it is available. Your machine may have a SIM card, or you can get one and install it. You remove the card from its little vestibule on the side of the machine's shell, and insert it into a reader or into a SIM card slot on some older laptops and PCs, and you can see all sorts of information that may shed some light on your machine's treatment of your UARS. I think it might help, and at least give you something to do. 😀