Is there any way to prevent player builds from breaking my tunnel, without changing the island setting for this?
You can add a prop manipulator device, use the area function so that just touches the props you don’t want destroyed and set to all props in that zone as invulnerable.
Does not work for these assets for whatever reason
Prop Manipulator
to make the tunnel indestructible
Mutator Zone
if you want to prevent the player from building in a specific area