Be aware that FCC rules will limit your output power very much with high-gain antenna, and in Europe, that will be even worse.(tighter rules) EIRP and directional antenna still need to radiate within some limits in front of antenna.
this will need to be taken into consideration for a commercial product.
I'd love to see this system work with low latency, and over 2~3km.
I was an owner and operator of a WISP about 10 years ago (ironically only about 50 miles from Gavin's market) and a telecom director of operations thereafter, I can say for certain the premise of what he's proposing is not only possible but relatively straight forward. What's presented is a little oversimplified at the layer 3 level but he's on the right track.