If you are not on Plus, your best bet is to register a CarrierService. Shopify will send all checkouts to that service. In your service, you audit the payload. Depending on the contents, like country, zip etc, you can either return a rate or not. This solves your problem.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…