I'd also consider thinking about using the "big ears, small mouth" technique to push up bandwidth; if a fixed link using a technology such as LoRa could transmit at a legal EIRP level, but coupled this with a really high gain parabolic dish (I'm thinking re-purposed satellite dishes) and low-noise amplifier at each end on the receive side, you could get substantially higher end-to-end Eb/No, and thus much higher bandwidth and range than would otherwise be legally possible. At first glance, the necessary hardware to do this looks quite doable, either by active RF switching between antennae, or the use of a hybrid/circulator to do the necessary duplexing. I'd be interested to see if anyone has already built, or even manufactures, something like this, and what the practical and regulatory barriers are to implementation.