Do you want your Island to be in the Skyrim World or create a new one? If you make a new one you can have the advantage to not break things and setup everything the way you want. You also have the ability to build your own environment. To do this you create a new worldspace from the world menu. I also think that you can take a look at my mood that uses an existing island in skyrim, maybe it i will help you see how I solved my problem. http://www.nexusmods.com/skyrim/mods/76314/? Warning:Never delete something from the original game! Better to make a copy of a cell and change that and when you're outside it's recommended to move any obstacles like:grass,rocks,icebergs houses and not delete them. Happy modding