Best carseat for air travel

I'm going to be traveling alone with my one-year-old in a few weeks and am looking for a second car seat to purchase for air travel. (We currently have a Diono Radian RXT in the car for him, which we love and I know it's supposed to be good for travel, but since I'll be alone I'm worried that the seat will be too much for me to handle, along with a very active baby, bags, etc.) I've been reading through a lot of threads that have a number of recommendations for lightweight seats, like the Scenera, Evenflo SureRide, and the Safety 1st Complete Air 65. Honestly, I'm just very confused, since there seem to be pros and cons for each seat. I'd prefer to keep costs to a minimum, so the Scenera and SureRide seem like the less expensive options, but my son is big for his age (26 lbs, 32 inches, wears 24 month clothes), and I'm worried about him outgrowing the seat quickly (we plan on doing a lot of air travel in the next few years). Any thoughts on the differences between these three seats and why you would choose one over the other?

Separately, since this is my first time on a plane with the little guy, I'm getting nervous about handling the logistics of travel with him. Any advice or suggestions on quickly installing the car seat and getting settled on the plane? I've seen a few threads where people suggested using a luggage cart or something similar to carry the car seat through the airport. Good idea? I was planning on using a very inexpensive and small umbrella stroller in the airport and gate-checking it, though that does make it difficult to also lug a car seat around.

Thanks in advance!!

I don't have a lot of direct experience with any of the 3 seats that you mentioned. My concern about the Cosco Scenera (and possibly the Safety 1st, which I think is similar) is that folks have decscribed it as difficult to get a good RF installation in the car -- e.g. requiring pool noodles to get the correct angle. It seems like the last thing you need is an installation challenge when you're tired from a long flight and dealing with an unfamilar rental car or relative's car.

You might also consider one of the Britax convertible seats, e.g. the Roundabout or Marathon. They are compact enough to go RF on most aircraft (or FF in a pinch, since your son is over FAA's recommended 20 lbs.) yet large enough that they will not be outgrown right away. They are also very easy to install.

If the Britaxes are too big and bulky for a solo trip, then the Combi Coccoro is another good bet and very lightweight. It will be outgrown sooner, but that seems like a reasonable tradeoff for the convenience.

In terms of getting through the airport -- we usually bring an umbrella stroller and put the carseat in the empty stroller. Then we gate-check the stroller. A smaller kid can be carried in an Ergo or similar (and most but not all security checkpoints have been OK with our kids going through that way) or an older kid can walk for short distances.

I've flown with 2 radians. If you are thinking of carrying them, you might as well make a massage appointment now. However, we just put them in an umbrella stroller (used a bungee cord to hold them both in there) draped my purse and diaper bag on the handles of the stroller, one kid walked and the other was in the ergo. Getting them both ON the plane was difficult, but a kind passenger stepped up both times and carried one for me (I was traveling alone). But any seat is cumbersome to get in a plane, IMO. Installation is easy and the low footprint makes it easy to get past the seat, and kid, on the plane too.

Also, my suggestion is pack light for the plane. As for installing the seat on the plane.

Put the radian where you want it, unfold it, then take the baby out if the ergo and buckle them into the seat. THEN run the lap belt through the path and install it. The seat has no room to fall anywhere once you set it down in an airplane seat. That's how I did it so the kid was tied down while I worked, lmao.

We just traveled using the Scenera for our 2 year, FF on the plane and RF in the rental. It is one of the ones without the built in cupholders, so a slightly smaller fooprint.
Pros - Weighs almost nothing, I used the top tether as a strap and wore it like a messenger bag while my guy rode in a gate-check stroller. Also carried my backpack. Fit easily in the plane and was easy to carry over my head thru the crowded aisle. Price! Inexpensive, if I had ruined it somewhere along the way, we could have easily replaced it without tears.

Cons - Not the softest material, they are not the greatest in rental cars, but we have a minivan and rented a Fusion, so installing carseats was not so fun for us anyway.