Hello Donohue,
we are only selling B2B.
The solution suggested by you is not enough, we are currently excluding the customers manually as described by your solution but this requires additional daily work. In addition to that, it does not help when a new customer register an account and then try to finalise a purchase. We noticed a lot of abandonment of new customers because of this 20% more.
We tried also to change the % of VAT to set to 0 because we sell more abroad than in our country but is not possible to make this change.