#P2P #AsynchronousCommunication options like #Briar, #NNCP and others also become very relevant. It is also quite possible to setup #NetNews servers like #INN to operate in such an environment, as it is what it was designed for in the first place (back when phone calls were the primary networking option).
There are also low bitrate radio-based networking options available like #LoRaWAN (https://en.wikipedia.org/wiki/LoRa#LoRaWAN), directional wifi relays (https://en.wikipedia.org/wiki/Long-range_Wi-Fi) would be usable in rural areas (and could be used to setup #Yggdrassil nets, again, and with very good bandwidth) and DIY #FSO (https://en.wikipedia.org/wiki/Free-space_optical_communication) can achieve bitrates competitive with rural internet: #RONJA (https://en.wikipedia.org/wiki/RONJA)
Definitely it requires dropping a lot of the current high-bandwitdh & low-latency programs & applications that have become so popular.
If you own your home and have the right to do minor renovations on it, do consider becoming a relay for various meshnets and other P2P and/or asynchronous communication options.