Do you have a means of acquiring patients initially?
Are you known in your community? Are you migrating an existing non-DPC practice? Or if you're starting from scratch, can you take some patients with you?
Needless to say, a way this isn't absolutely necessary, but it will makes things easier on you (financially and psychologically).
A note on non-compete clauses: they are difficult to enforce in many states (
source) so don't be too intimidated. Check out the appendices of
this guide to see your state's statutes on physican non-competes. Also, don't be afraid to simply ask your employer to waive the non-compete clause.