I’m not sure if it’s what you’re talking about, but our stroller of choice over our double Bob is the chariot...it’s a bike trailer but converts to a stroller. Just easier with multiple little kids. I was going to post a pic but I can’t get it to work. Anyway, according to my measurements it’s right at 31x43 so we’ll see on our next trip I guess.
I have a double BOB. It’s pretty big. But still have half an inch to spare on the width.
Interestingly, yesterday I saw someone with one of those things you attach to a bike... it fit two kids side by side. I’ve never seen one used like a stroller before.