Why not make it like Engineering?
You do your 4 year undergrad and at your first job, no one trusts you. Your supervisor/senior engineer checks Everything you do. You are reserved for paperwork and unskilled manual labor which is also checked. After a few years (4) you get some Freedom, but still checked by your seniors. Anything important, even when you are a senior engineer goes through your Managers and directors.
I don't see why this system wouldn't work in medical. We build airbags and bridges. Both safety critical.
I would even say having 1 physician is more dangerous than having a team of Engineers with less Schooling.