air bag for neoair

It's easy and cheap to just buy an Instaflator. It's a very long plastic bag tube with a connector piece already attached. You can cut it down and still have an effective inflation bag. I'll post a link later unless someone beats me to it.

Even though your Gear List doesn't show one, are you taking a pillow?

And if so, would you consider an Exped Pillow pump instead?

With a little futzing around it can be made to mate with a NeoAir.

Found the instaflator, great idea, watched francos video on them. Easy solution, just ordered!

Fair warning on the Instaflator–I have found them to be somewhat fragile. I have used one to the point of no longer being usable in about 20-25 inflations (though, in fairness, I could have been much more careful).

If you're looking for an inflation bag, I have found the Therm-a-rest branded one to be better than the Instaflator for durability. For a thru-hike, that'd be my recommendation.

"I have found them to be somewhat fragile"
Yes they are..
It is a bit like the thin disposable type shopping bag.
The easiest way to puncture it is to dig your fingers in particularly if you have long nails.
However it is very easy to patch up with standard sticky tape.

If you use a trash compactor bag as a pack liner, you can use that, much like the instaflator. I have used both. But since I'm already using the pack liner, I quit carrying the instaflator. Just takes 2 fills and a top off breath for my size large xlite.