My kids biggest moan is that they can't see anything in the 2nd row seats, my daughter is touching 6ft and has to peer through the alpine lights and every bump hits her head on the roof!
I'm not sure rear side facing will be any better.
The two boys are a bit shorter but I wouldn't wish them pair on anyone plus mines a puker!
The two girls can't be separated and I get that, so they need a Disco or something but not a tratter.
Kind offer noted though Flatlander and I may be calling on you but I suspect, if I do, that you'll have my Doris and/or 2 boys. I might put a request up for a Disco ride for the girls.
My worry is the whining from the daughter there after about Discos being "sooo much smoother/quieter/ comfortabler/ than dads old tratter.