Why not do something like survival? Private chests are like needed. I don't trust many people and ik @BakedGoodz doesn't either so maybe add this?
that would be really helpfull if you dont want them to access your chests and your ender chest is full and so people dont steal your items ( like when some one stole all my stuff in skyblock)
The only people who can open chests on your island is you and your island mates. None else. If you invite someone to live with you on the island, you are putting trust into that player to access your chests anyways.