The obvious solution is class D.
I don't believe D is suitable for other than TWR ops. and I think (I could be wrong) that it is only used for that purpose elsewhere.
I don't have the books handy, but doesn't it use in part separation involving VFR by reference to visual features i.e. "track north of the xxx Highway"? Something difficult for an enroute centre to handle, and another class of airspace (in addition to A/C/E/G) for them to manage.