I remind me of an idea I had once for a hidden-hidden-service: Put a small SBC with a battery and a solar panel in a small box, find a street-accessible free-wifi, fix the box to a electrical post or similar and connect it to the free wifi. On it, run a Tor Hidden Service. They don't need NAT rule since they can do NAT punching and such, so if the wifi is not too aggressive with what it block, you should be able to run the hidden service and have it accessible from the outside. Bam, you have an hidden, hidden-service :)