When I discovered Meshtastic, I already had some of the Heltec modules around, which are reputed to have the worst RF performance. I tried anyway, and indeed, I had to equip some truly silly antennas to get even a mile of range. (18dBi yagi in my living room, pointed at a parking structure downtown, was able to talk to another node on top of the structure with a 6dBi omni. Just barely.)

I've been pursuing other projects since then, but a quick skim of the meshtastic forum suggests that there are some much better-performing RF modules now. I'll play with those soon enough...

And anyway, there are encodings other than the patent-encumbered LoRa worth considering, too. (The LoRa folks just did a stellar job capturing mindshare lately.) Really, a feature-set identical to the original IM-ME, but with an option to use ham radios to extend the range, is what I want.

By now we have very efficient modulation like FT8 and LDPC error-correcting codes, so I think it should be possible to do much better, even within Part 15 limitations.