It has become really hard here (YewEssay) for me to find decent-sized boxes that hold long-wheelbase tourers; even with extensive disassembly it can be pretty tight.
Dan, you might look at this source of boxes, in Chicago:
https://www.shipbikes.com/buy/They make a range of sizes & shapes. I have an "eBike" box, which I used in Feb/17 to ship my Eclipse to Australia. The linear size is 85" -- approx 43 x 32 x 10. That proved to be very spacious. It swallowed my medium-sized bike with no disassembly of the frame & forks, and I had a lot of extra space for shoes, helmet, water bottles, seat bag, etc. I removed only the wheels, seatpost, fenders, bars and pedals.
The cardboard is quite thick & sturdy -- Shipbikes says it should be good for about 10 flights. Shipbike includes a kit of bits to protect vulnerable parts--a pair of flat mushrooms for each wheel, stiff tubes to hold forks apart, etc. (No guarantees against wanton barbarism by baggage handlers, of course.)
One caution: Not every airline allows an 85" box without extra (possibly prohibitive) fees.
Last Feb., as we left Ottawa, the guys at the oversized baggage kiosk decided that they simply had to open the box to inspect the bike. Luckily, I was at the front of the queue--the skiers and surfboarders behind me fretted and steamed, and all I could do was to raise my shoulders, palms outwards, and roll my eyes. The Shipbikes box opens easily and quickly, because it's laid horizontally on the ground, and one larger outer box fits over the smaller inner box. Remove the outer box, and the contents are exposed.
(If we have the same rigamarole in three weeks' time at the Ottawa airport, it's going to be a more complicated bizness: My Raven sits snugly in a cutdown bike box, 38" x 32" x 10". Only the lid, 10 x 38, can be opened, and not easily at that. When that's done, only bubble wrap and handlebars are visible.)