The cheapest fares on United allow you to bring only a personal item, and United's size limits for personal items are more strict than any other U.S. carrier -- 17 inches by 10 by 9.
The late, great Night Flight Travel Duffle was sized perfectly for this use, but TB has told me they have no plans to bring it back, nor can they say whether any planned designs would be a good fit. And there's nothing in the current TB lineup that wouldn't be a serious compromise.
The Stowaway supposedly was designed with this use in mind, but it's substantially smaller than United's limits (12 liters vs. roughly 22 or a bit more), and it has too much organization to suit many people. The mini size of the Yeoman duffle is closer to United's limits (it's 17 liters), but it has no organization at all, not even an external pocket for cell phone, wallet, and keys. The combination of a mini Yeoman with a side effect might be workable, but it would be an awkward compromise.
Yes, I could troll ebay, the FB "for sale or trade" group and other places for a Night Flight, but the demand for them is high, and owners rarely part with them.
Among companies that make good quality bags, the smaller size of the Tripper duffle from Timbuk2 seems like the best possibility I've seen thus far. It has enough organization, and though it's a bit oversized one could probably get away with it:
https://www.timbuk2.com/collections/...per-duffel-bag
Any other suggestions for a bag that's both useful and takes full advantage of United's limits?
Thanks!