Outdoor access point options

Looking to install an access point on the roof of a boat terminal (roughly 200' wide and 200' from the actual boat docks) what will provide internet access to incoming boats while they are docked. The only client on the network is going to be the network video recorder which will allow the company to download video footage if needed while the boat is docked.

What would be a good Ubiquiti product that will provide somewhat wide coverage (200-300') and a fair range (200' minimum)? This will be mounted on the roof in a salt/brackish water environment.

I've used NanoStations before for point to point before, but obviously this would be for multiple clients to a single AP.

Thanks!

*UPDATE: based on the responses, going to give the AC Mesh Pro a try. Thanks for the help.