I don't have any experience with the Arystone system. But, I've designed RF stuff professionally for >30 years and have some personal experience with Wi-Fi through the woods.
Read and understand this page - real line of sight requires an understanding of the Fresnel zone.
wireless farm networking meshing outdoor wifi for rural locations
ayrstone.com
Trees, especially ones with wet leaves absorb 2.4 GHz signals amazingly well, unfortunately.
When it comes to Wi-Fi 'range' , it's not the distance as much as what occupies that distance. 5 miles through outer space is easy. 500' through the woods - not so much.
Personally, I'd be leery of their system and would only go that route if there were no other options. A mesh topology is complex and you don't get as much data throughput as a point-to-point topology. Mesh has more ways to fail.
Have you done any experiments? If you're keen to tinker, you might start with some simple 2.4 GHz access points as high as you can get them, and see what you can achieve. Something like a TP-Link CPE210 is inexpensive, reliable and decently easy to set up. I have that setup to an outbuilding - it just works. It has a directional antenna which will mean you have to point it in the favored direction - might be OK, depending on where your gate/cameras are.
CAT5/CAT6 is limited to 100 meters, at least by the book. It also opens you up to lightning damage (ask me how I know!). Fiber is the best, if you are willing to trench it in...