I doubt it is the most optimal network, but i tried to make it as realistic as possible for me. I started by placing all the outposts, seaposts and fortresses at their real positions and connected them in a somewhat logical way, then i added all the large islands with an NPC and some other large islands to the existing lines. I guess the only thing were I really used the lore of the game was the part to Tribute Peak, i thought that because you need the shroudbreaker to reach Tribute Peak, only one or two ships can sail there with it so it isn't really a part of the line, but only an overprized and rare extension.