Technically, you can practice after an internship only in most states...but your job choices will suck. Trust me, insurance companies do not want to insure a doc who hasn't completed a residency and become board certified or at least board eligible.
I have a friend doing urgent care (the only thing he can really) for $55 an hour. They move to NPs/PAs like most other places? He's hosed.
Do the three year residency...the world is then your oyster and you can pick and choose jobs at your leisure.