Place as the novel's argument
Every regional novel makes an implicit argument: that this place is particular, that the life it generates cannot be generated anywhere else, and that attending closely to it will reveal something true about human experience that a more placeless story cannot. The craft is in building that argument into the structure of the novel rather than stating it. The place should be present in every scene: in what the weather makes possible, in what the economy forces, in what the landscape permits, in what the local history demands. A scene that could happen anywhere is a scene that is not yet fully regional. Keep asking whether this scene requires this place, and revising until the answer is yes.