I don't see that owning an aircraft would be unworkable. A flying school wanting to have all instructors working at the same time will need at least one AC per instructor. Therefore one instructor with his own AC (perhaps something a little more flash than the usual to attract business) should be able to make ends meet.
A service like Moneypenny could be used to handle reception. There's no need to employ a fulltime receptionist. They could also implement online booking for minimal cost.