Puzzling car seats/3-across

[lalasmama]

Vehicles: 2012 Ford Explorer and a 2007 Buick LaCrosse.

Car seats: 2 Cosco high back combo seats. 3rd seat yet to be determined: convertible RF for DGS, who has nearly outgrown his infant seat in length.

Any idea if we can just do a Cosco Scenera for DGS3's convertible seat, RF, between the Cosco high-backs, in both cars? And if the Scenera won't fit, any idea on what would?

Honestly, the idea of driving two cars to BRU, installing the seats in each car to check fit, on my own (DH doesn't "do" car seats, it's all me), sounds slightly less appealing than prepping for a colonoscopy.

Car seats are only used 3-4 days a month. Right now, we put the high-backs in the 3rd row in the Explorer and the infant seat in the middle row with DD, but DD isn't going everywhere with us anymore, so we'd prefer to be able to puzzle all 3 into the middle row of the Explorer when DD isn't with us.

[Joolsplus2]

I'd think it should work, the Scenera NEXT is $44 at Walmart and absolutely a piece of cake to install RF.
The kiddos in the HBB's are really tiny, right? Make sure they don't have shoulders going over the top slots (I feel like we've determined those seats are ok, but I always make sure!)

[lalasmama]

They are newly 3 and newly 4, and still have a good amount until they reach the top harness slots--just barely past the bottom ones now. Wasn't my preference for long-lasting seats but DH knew they wouldn't last for more than a year or two before buying something new. Pretty penny wise but pound foolish, but he feels like he got his way.

[Joolsplus2]

Yeah, those seats aren't not a bargain for small kids in a small space . (My memory of mine is at least that it was comfy, hahah, my mom bought it even though I told her the only criterion for my 2 yo and one on the way was to buy a seat with a '5 to 40lb limit' and this was 20 to 40, d'oh!, and it had the most complicated primitive single strap harness I've ever seen, not even as simple as the one they have now, it was frankly bizarre, and twisty...I ironed it! Oy). After the harness you can move right to a narrow backless, since they are usually bad as boosters.