We used an Atlantic Tower arch to hold two 315W Panasonic panels. It worked well, and we are happy with the result. We are currently at Lauderdale Marine Center if you wanted to stop over and see, you would be welcome.
I liked the Atlantic Arch because of its light weight. Installation of the arch was a two day project. Another day or two for the panel install.
On my old boat I had panels on the rail. On my way east from Hawaii I ran into a “bit of weather”. We took a wave across the boat that threw green water against the back side of the leeward side panel, which were folded down. The panels were fine, but the rail they were attached to sutained significant damage. That experience has made my leery of rail mounted panels.
Fort Lauderdale, FL