Maybe I am clueless, but I don't understand what need there is for nurses. A mid-morning couple-of-hours listen-to-music-ROM exercise/massage CNA-type student was all we (our son and I) ever had, and that was for extra hands and socialization for Larry, not anything medical. What are these "skilled" people doing?
I only ask because some of you seem understandably concerned about finding and paying such help, and I don't think most of you need to be.
As for turning, Neil, Larry couldn't be, (250#, subluxated shoulders, dicey spine/eyes/everything) so we didn't have a power mattress. He was on his back/butt for >3y. We had a powered bed with a standard hospital mattress and on top of that a low-voltage heating pad that was almost always on, and on top of that, a 2" foam overlay (not the cheap yellow egg crate stuff).
I have previously published our travel pillow/pieces o' foam for the arms regimen, and of course he wore pressure relief boots. Most importantly, his bed was never anywhere close to flat. His legs and upper torso were always [differently] elevated. I understand that it is only your wife at night, but likewise, I was the only other person in the room so on that score, so like the others, I will say that it can be done.
Do you know when/why you are making noise? Is your BiPAP mask uncomfortable...does your back hurt...? In other words, what does she do at night to fix whatever problems you have? There is probably a way to head some of them off at the pass.