I'm just back from a one-bag trip to Iraqi Kurdistan. I had my Osprey Farpoint 40, and a plastic bag for putting under the seat. I had a wallet, front-mounted bum bag, and a coat with usefully big pockets.

It worked fine, but there is some refinement to do. In particular electronics need to be slimmed down.

As well as making it easier to get on to/off planes, it was useful for the shared taxis that are used for inter-city transport. They are just normal cars, and with typically four passengers boot space was often tight.

Also, on coaches I could keep all my luggage with me, so didn't have the risk of forgetting to collect my main bag from the storage. It also gave me something to hug for comfort when I found that yes, this coach is going to drive 100 kilometres along the Syrian border rather than take the more northern roads I thought it would