We use a Red Oxx Large Aviator (no longer available on Red Oxx web site, perhaps still available to order by phone) as our souvenir bag. It is huge and very tough. It travels folded up in our checked bag on the way out. Depending on where I am going, I will either locally source, or fold-up and bring a large cardboard box (like the big vegetables ones at Costco). We have checked the bag a few times loaded to the 50 pounds limit imposed by airlines, and it has held up great. The bag is really difficult to carry fully loaded/weighed down though - not a fun time getting to the check-in counter at the airport.
The 2-inch webbing that wraps around the bag is what gives it such carrying capability, but also what limits how small the bag can fold. The webbing is much stiffer and thicker than the Cordura 1000. I carry the Aviator on the outbound in roughly the same shape that Red Oxx ships it in (folded in thirds, handle on top).