It's so important to work together - compromise - we're all in these horrible flight situations, every time we fly. Flying as a fat person, I get looks, stares, sighs, and I always do my best not to take up more space than necessary. It's not easy for anyone. It's not easy for the people stuck next to me, and it's certainly not easy for me, clutching my arms across my chest for hours at a time to not encroach on their space.
If you have a little kid behind you in a carseat, and it's not a hugely long flight, maybe just recline 2 inches instead of 3, and if you're flying with a kid in a carseat, remove their shoes! Work together!
I was on an overseas flight last year, sitting in front of an older couple and their adult special-needs daughter. I was wearing my very long hair in a ponytail. The mother leaned over to me and very politely asked me to move my hair out of the way, as her daughter tends to grab things. I immediately thanked her and braided my hair over my shoulder so it would be out of her daughter's reach. The daughter kicked my seat throughout the flight, and normally I would turn around and give a kid the stink-eye if that happened, but having been given the knowledge of her situation by the parents before the flight, I knew that it was not being done out of malice and that a long flight must be especially difficult for them all, and I managed to ignore the kicking. (A sense of righteous compassion will make anything endurable.
After the flight ended and we were disembarking, the parents apologized to me profusely for all of the kicking, and I smiled and told them it didn't bother me at all, and welcomed them to New York City.
I felt good after that flight despite my lack of sleep, because we had communicated beforehand and gotten through together with mutual understanding. Sometimes that's all it takes.