You could run something like Reticulum + LXMF over airMAX to WAN links
https://store.ui.com/us/en/category/wireless-airmax-5ghz
Think like a SV2 proxy that does a couple of airMAX hops to some point that has internet access.
Reticulum packets are under 300 bytes, by far the least amount of bandwidth of any protocol I've seen.
https://github.com/markqvist/LXMF?tab=readme-ov-file#wire-format--overhead