I recently struggled with mounting a 17" x 132" panorama for a client.
My framer and I tried a few options.
My initial thought was to print on a reasonably tough paper, and dry mount to gator board, which is how I've been mounting panoramas lately. My client liked the no glass look, and was OK with re-printing the image if it ever got damanged.
The concern that my framer and I had, is that it's awfully easy to introduce subtle ridging when you mount on gator board, because of having to take multiple bites in the dry mount press. It can be minimized by adding an oversize board under the press head, but I find that sometimes it still happens (if anyone has a solution, I'd love to hear about it).
So we laminated a back board out of overlapping layers of mat boards, and figured out a pattern of mats for the front mat which would let us use standard 32" x 40" mat boards.
This didn't turn out as brilliantly as we'd hoped, and so we eventually went with cutting the image into multiple sections, each of which was only 40" wide with mat.
I was surprised to discover that this actually worked out quite well. The client was happy with the look, and I have to say that the multiple frames option was an awful lot easier to handle than one huge frame. It ended up going around a corner in the client's board room.
My next panorama is 24" x 144", and I'm thinking that it's time to give canvas a try.