Tall 3 year old on plane

I'm pretty sure I'm going to be stuck bringing the Foonf, but just in case I'm missing anything I thought I'd post.

I'm flying alone cross-country with my 3 year old in a couple of months. She will be 3 years and 9 months at the time. Right now, she's almost 42 inches and just over 40 lbs. I have flown with her and the Foonf before, but she is VERY uncomfortable in it forward facing on a plane. She was so uncomfortable in it that I ended up just having her on my lap the whole time. Not to mention, that thing is super heavy, and I will have her, a stroller, both of our carry-ons, and the car seat to deal with by myself.

I'm not willing to FF her at our destination. I will on the plane, of course. The seats I have that she still can RF in are an Axkid Kidzofix, an Axkid Mini, and the Foonf. I need one more seat and thought the problem would be solved and I'd order the nice light Britax Two-Way to take with us, but I've just realized the seat is 18 inches wide and the plane seat is 17.2 inches wide. Not going to work.

She is too tall in the torso for a Radian RF. She's just at the height limit of a Peg Convertible, and I she's too heavy for anything else.

Does anyone think there's any way the TWE will be ok on the plane? It would really only overhang half an inch on either side. It would fit at the buckle I believe. I have flown with her many times, and nobody has ever once looked at or objected to her car seat, and I doubt they ever would. I could put her in the window seat and me in the middle next to her and then it would just overlap onto my seat.

I have had someone check for FAA approval for every leg of every flight I have ever taken a car seat on (that's about 5 or 6 times, I think). I wouldn't count on being able to sneak an unapproved seat onto a plane. Is the TWE approved by the EU for plane travel?

I doubt the width will be an issue other than for your own comfort having to sit next to a wider seat.

Which airline are you flying? A lot will allow ECE or UN stamped seats (I know Delta and AA do, but I'm pretty sure United and SW don't.) If they do, you'd also want to print off that section of the website since they probably won't be used to seeing those stamps. I've only had 1 FA ask to see the airplane approved label, and that was on United. I've taken DD's car seat on board about 50x by now (we basically can't fly anywhere non-stop, lol.)
Just don't sit bulkhead, raise the armrests, and it should fit fine. The width would be the least of my concerns.

When I flew last week (Alaska), a FA practically ran down the aisle after me and made me stop doing my install and show her the sticker. All the other flights I've taken with a car seat have been on Hawaiian and they asked as I boarded the plane each time.

As I was deplaning, the FA was discussing the car seat situation with a FA-in-training and talking about how to find the sticker and what to do when the seat is NOT approved (she acted like this happens all the time) and I stopped to chat with them a bit so she could show my seat to the FA-in-training.

I am surprised to hear that it's so common to be able to get onto a plane without having the stickers verified. I suppose I only have experience with 2 airlines, but still!

See, I've never flown either Alaskan or Hawaiian, ha! We may be on an Alaskan leg this summer though so that's good to have a heads up.

We're flying Delta, which I think is the only airline I've ever flown with her. But we fly all the time. I have literally never had anyone give a second glance at her seat. And we've traveled with at least 4-5 different seats. How weird. I don't know if it's EU certified.

Maybe I'll get the TWE anyway and just have it shipped to our destination. I really love the seat and how easily it installs. I had one until last fall when my mother let my daughter rip all the styrofoam off it when I had it in the house for cleaning...