What Is A Low-Cost High Range Communication Infrastructure

As mentioned in the title, I'm looking for types of digital communication infrastructure that can operate in *extremely* low infrastructure regions, ideally low maintenance and use cost (even at the expense of bandwidth). The concept is a backup network to communicate between rural towns in a region similar to Siberia that have little to no connecting infrastructure.

The infrastructure would have to be

1. No physical connection between nodes
2. Able to operate in swampland, relatively flat and low but heavily forested terrain
3. Exist in public frequencies
4. Have a range grossing 100km

Possibilities I know of so far

- Satellite internet:

Low setup price, low bps, subject to niche ISP, knocked out by clouds which are common in the region (starlink looks preferable but is not yet available and is also facing issues politically in the country)

- HF Radio:

Legally complicated, requires antennae and a not-negligible amount of power, low bps