I know it isn't overly helpful, but I break down my airline thinking into groups:

1) in the event of a airline crash.

In this case, I mostly think about this in terms of escape from the plane. Sensible shoes, natural fibers, flashlight (on person, not in bag).

2) being stranded in the airport/airplane.

What items do I want with me if flights are canceled and I'm stuck in the airport security area for a day or two.

In the context you describe, spending a bunch of time in an airport seems semi-likely.

Things that come to mind: A book. Clothing to keep warm (I like an expedition weight Capilene top + a fleece jacket + warm hat). Snacks. Asprin/etc. -- stuff in case you don't feel well (which seems semi-likely). Water bottle. Toothbrush (even if you can't bring toothpaste).

I'd skip the sleeping bag. Seems awful bulky. Just enough clothes that you are warm enough if you have to sleep on the floor or whatever.

Cell phone. Way to charge cell phone both if you do and if you do not have wall power.

Cash, credit card(s), travel papers.

3) what do you need when you reach your destination.

This is probably hard since it sounds like it isn't clear where this will be, nor how long coupled with very limited amount of stuff. Seems like you are going to be somewhat at the mercy of what you can buy when you get there.

Certainly I'd have a lightweight rain shell which can be layered on to of the top + fleece noted above.

It is kind of painful since you need to prepare for both hot and cool, but with limited space.

-john