Thanks, there's a number of soft bag options, but all have the same problem of a relatively bulky 'second bag' to lug around when not flying. I'm an ultra-light camper and tour out my single 30L T-Bag which I absolutely adore - its unique integration with the bike was key in rekindling my interests in bike touring after quitting decades ago.

If using a soft bag with cardboard liners, I think the minimalist IKEA Dimpa bag might work best for me. That said, my rig is still too new and cherished for to hand over to the Gorilla baggage handlers.... I'll have wait, or get another, before fly-touring.