Well there doesn't need to be a fully working, always up internet connection. A satellite connection will do just fine, and these tend to be available at camps.

Well there doesn't need to be a fully working, always up internet connection. A satellite connection will do just fine, and these tend to be available at camps. One way of doing this would be with state channels, where most of the oltp is done off-chain and signed messages can be relayed via sneaker-net until an on-line node is found days / weeks later.