Be careful you don't forget and leave ammo/magazines/pistol in the bag when you go to the airport.
I like the idea of a small backpack/shoulder bag. I've got one with my old CZ75 Compact and various other stuff in it. Another one with my Shield 9MM in it. And the latest one has my Shield Plus and other stuff in it. Each one gets a little bigger as I decide I want to add one thing or another in it.
I only carry them with me on road trips (my car/truck). Extra mags/ammo, knife, flashlight/batteries, small cellphone charger and wire, IWB holster so I can conceal carry the pistol in the bag if I lose my primary carry pistol, small first aid kit, etc.