Pretty Dangerous.
The VA will likely try to be "helpful" and maximize your rating, which may well cross the threshold to a diagnosis. If that gets put on paper, good luck sorting it out.
I would try to avoid a sleep apnea like the plague. Airline pay is a lot better than VA disability.
Or just roll with sleep apnea and accept that there will be FAA hoops. But be very careful trying to have your cake and eat it too. If there's any grey area at all, note it on your FAA medical form in writing. That would at least prevent any fraud issues.
The DoD/VA are pretty loosey-goosey with medical stuff like this. The FAA will go hard-over on you.