These guys go good work. Know several happy customers
https://www.atlantictowers.com/custom-towers-hardtops.php
Actually might hold up better than a welded structure.they have a top in a box that they sent a picture of. it has pivoting mounts and I wonder if they are going to stay tight banging across the ocean. and its only 4 pipes vertical.the price is right but I am worried about long term.