Those SW dimensions are odd, because of course if they are linear inches nothing would work. It would seem odd to say that you can ship a bike, but then publish a size limit that no bike box would meet. I wonder if they might mean max length/width dimensions?
I have an older Scicon hard case, that I use for my 58cm trek Emonda (with seat mast, which is the tightest factor). I’ve done a dry run with my 58 checkpoint, and it looks like it won’t be an issue even though the frame is a bit longer, but the seat post is fully removable.
I would love a way not to remove the bars, but I would rather deal with that than go with a soft sided case. I think if I got a new one I’d look hard at the Pakgo as well, it looks good. But I would definitely stick with a hard sided case.
And I speak as someone who works around planes all the time, and did my time as a baggage handler many years ago.