Sounds like you have a real trooper on your hands! (More power to ya, Libby!!
Unfortunately, I have absolutely no suggestions for how to get her to sleep on her side or with her mouth open. It might help if you could describe how she sleeps now? With her head between her paws or on your pillow?
Does she have trouble settling, or does she settle, then get restless when she finds she can't breathe? Does she sleep on your bed, or on her own? Will she use a round dog bed?
Perhaps some other members will have some ideas.
It does sound like Libby cherishes life and loves her mommy. Hard on you but good on her! (Priscilla was like that, too.)
Hang in there, Mary. You're giving Libby the best gift in the world--your love.