Where are you based? We’ve worked on a lot of marine and marina wifi solutions here in the UK and would love to help.
I wonder if you have checked for 4G availability? Cellular can be a surprisingly good fit for marinas so long as you heavily filter and block the heaviest bandwidth consuming activities (like video streaming and OS updates).
With a MAX or Balance managing the internet access, you would also be able to manage the Peplink range of Access Points too for WiFi distribution across the marina. Or another approach (assuming you have cellular connectivity) is to deploy multiple BR1 IP55’s which can supply internet connectivity from their inbuilt cellular modems over their inbuilt WiFi APs.