Briar mentions "mailboxes", where you can stick up collectors wherever you want. It's not as nice as repeaters that would build a multihop mesh network for you, but one advantage of not doing multihop is that you get at least initial insecure identification before any identifiable secure communication is attempted so even if the Military Police are watching you, they won't be able to tell you even have Briar unless they can spoof a device for someone you have as a contact and have a waiting message for (or the BLE device ID of one of your mailbox devices). Those aren't hard to spoof, but learning what they are can be more difficult than if you're broadcasting to anyone that will listen like multihop requires.