Probably the best idea yet. It's definitely not foolproof though. Best you could do is put a security chip in the camera that digitally signs the pictures, but that is imperfect because eventually someone will extract the key or figure out how to get the camera to sign pictures of their choosing that weren't taken by the camera.

A creator level key is more likely, so you choose who you trust.

But most of the pictures that would be taken as proof of anything probably won't be signed by one of those.