So I had an interesting thought while trying to come up with story seeds for my fun little adventure.
Magic beings, creatures, spirits can create Regios. Said magic being can be the embodiment of a ship. Thus the ship has an aura, an aura that moves.
But a regio is a separate contained space sort of connected but also sort of seperate from the physical ship it embodies.
Could House Mercere enchant a Gate inside the regio, linked to a gate elsewhere, that will still operate even as the mundane space the regio is linked to moves about the world.
This could be a super interesting and fascinating adventure set up.
I would do it as the regio is the "Home port" of the ship, which it can access at any time, and looks like a hidden priate sort of cove. Then put the portal on the island.
I think it would depend on a lot of things, including the "depth" of the regio- shallow regios are supposed t be similar to the place they are anchored to, so a regio anchored to a shp would seem to me to likely also be a ship, at least in essence. The closer you get to the magic realm the better the chance it could be stable- though on the other hand one would not expect a cosm of the ship to be essentially anchored in space either. Like I said, it really depends on the regio and how that particular regio is going to function. In principle you could have a regio of the forest that the wood the ship was built from was taken from.
I like the idea that the initial regio level is to close to the moving ship that even though its bigger than the ship itself its too unstable for a Gate. BUT the second, or maybe third, with the level depending on how difficult I want to make the process, is stable enough / close enough to magic, that the gate works.
I can also see much potential in the ships are made of branches of a particular magical tree. Using magical connections the ship regios can link to the regio in the pocket space of the tree, which is stable enough to allow for a Gate.
Ritual Creo magic to create a Golden Oak (or some other magical tree) plus some work to awaken the spirit to make sure the ships built of its branches are linked could be an interesting element.