Okay!
Here are the clean and empty neighborhood templates for The Sims Castaway Stories.

Note: You need to replace your current NeighborhoodManager.package file in order to bypass the story and unlock all story rewards.
If you don't bypass the story, the game might crash then, because it would search for sims who don't exist in the neighborhood... so you'd get nothing but errors if you didn't bypass the story.

Known Issues:
No issues for Wanmami island but Felicity Island...

It was really hard to remove the hard-coded story from Felicity Island. Simple re-numbering and changing the neighborhood ID didn't work...
Well, the story's gone now - so it's a free neighborhood like Wanmami Island...

But it's not perfect yet. The story rewards are all there in my game, however, the travel button is grayed out. Fortunately, you CAN travel but you have to click on the portrals if you want to travel. I'll update Felicity Island if I found out a way of re-enabling the travel button without enabling the story again.