What I do is buy Vaseline after the security gate. I then put on my diaper and vented latex catsuit. I board with the need assistance crowd and upon arriving in my seat (I try to get the middle so I can stretch out in both directions) I vaseline my butt and squeeze it in.
When the window seat person (hopefully a hot female) crawls over me (the vaseline smooths that) I had over a diaper with a polite smile and say, Im taking a Xanax, its 14 hours, here, have a diaper.
Then I put on my eyeshade and off to dreamland until landing.