count the through passengers, and then you can get up and move to a better seat. My guess is they'll know that you're the one that got off and maybe ding you for it. Seems I've been reading about people doing this more and more, even an app designed to figure it out for you, and the airlines are adding specific prohibitions to their ticketing regarding it. I'd look around a little before you decide to do it, there may be a penalty.