Well I'm sure you know this but the way we duped in past games was by resetting the game in the middle of some gate shenanigans. With proper timing, the items remain both in the town and in the visitor's pockets, as I recall.
If the game is constantly saving whenever you do or affect a thing, like the Souls games, then even if you reset you'll still have lost the items to the visitor.
You might be able to manually save, but simply not be able to load anything but the most recent save. If an autosave (to the cloud) occurred after a manual save, then that's what the game loads. And because they're in the cloud, they should theoretically be tamper-proof from save editors, at least for most people.