A summit registry where you sign your npub and comments? Perhaps with a relay that only accepts connections over something like bluetooth ensuring that you're actually at the summit, but then publishes out to the broader 'net? The networking there could be tough of course...probably need a starlink, solar panels, and something to keep it all waterproof (and preferably, not too covered in snow for the solar panels to be covered). Not the easiest thing, but not impossible. Just not sure how worth it it would be.
Discussion
Wow this is a really strong idea, but it will be really difficult to implement. I'm currently thinking about something simpler
Another alternative would be to take a page out of the secure scuttlebutt (or Briar) playbook and built a relay system that works on sneakernet, allowing say, hikers on a long trail to maintain their own relays on their phone, make their posts, and then sync up over bluetooth or ad hoc wifi to store and forward.
Not sure this really works with how Nostr relays do things though, but I do sort of like the slow organic roll out of such a network. The biggest downside I see is that we may be a bit late for this, given that at least on the American longtrails, you've generally got enough internet access that at best this would be a quaint curiosity.
Perhaps the most immediately useful thing would be using the "Around Me" feature Amethyst (and some others I believe as well) have, particularly in trail towns to get a feel for the lay of the land. Nostr's a pretty friendly crowd, and while many trail towns are too, it might be helpful to make those connections online, especially in less than ideal weather.
Then there's something that would absolutely blow up if integrated, which is to reach out to Guthook and have him build out the FarOut app as a Nostr client.
there is definitely something to think about here