Great write up. I could see something like this working at a marketplace (or major conference with terrible reception). I don't think total offline would work well at all, some people will need to be online. But this could be on some of the merchants with a data plan. The ones with internet could be the hub(s) and the users and other merchants could have their channels with the hub(s). Then routing could take place.

It's probably only worth it if users at the end of the day could go home or get internet access later to verify the chain and channel state. Otherwise the hassle would be too much, it might as well be custodial.