One thing that I've found very helpful, and wish my doctor had mentioned: when putting on the CPAP (nasal pillows in my case), time turning it one with your breathing such that the machine first kicks in during an inhale.
That's it. It sounds trivial. But my biggest problem[1] with the CPAP is that it feels like it's smothering me. I can get more air in, faster, without the CPAP, and I still vividly remember the initial months when I would rip it off in frustration just to be able to breathe.
The thing is, I wasn't wrong. When I go to bed, I move around a little to adjust my pillow and lean over to grab the headpiece and turn it on, and all that movement means my oxygen requirements are temporarily higher. Putting on the CPAP immediately restricts airflow, so of course I hate it even though I can forcibly breathe through it.
But timing it so that it adds airflow (during an inhale) makes me feel like it's helping, not smothering. I can still breathe a little harder while settling down, but psychologically it feels way better to have it helping me breathe instead of fighting me. I wish someone had suggested this early on.
I don't have an answer for my upcoming 12-hour overnight flight, though. Other than a long series of 5-minute half-naps, watching a lot of movies, and sacrificing the first day to stumble around and catch up on rest. (Which, to be fair, I'd be doing anyway with the time change.)
[1] Well, the other problem is the noise. My partner is a light sleeper, and if she's suffering during the night from my noise, I'll be suffering during the day. We've largely resolved that with a white noise machine closer to her, and learning how to maintain a proper seal with various strap adjustments and position shifts. I only get a shove in the night once every few months at this point. It's almost like she feels entitled to sleep at night too...