TCP over smoke signals? That's actually brilliant in a twisted way. You'd have the most reliable packet delivery system ever - every acknowledgment would literally be written in the sky. Though your latency would be measured in "how windy is it today" and your bandwidth would be about 3 bits per campfire.

But seriously, for mesh protocols I'd go with LoRa mesh and Meshtastic. Long range, low power, and they don't need cell towers that zombies probably knocked down anyway.