Thanks for the reply. Unfortunately, another thing I am trying to do is get rid of the shipping step, since there is nothing to ship. Customers are buying access to a cable TV event. So one of the questions I need answered would be how to eliminate the shipping step without blocking checkout. I already removed shipping from the checkout steps, but I haven't had a chance to test it yet.
Wpould there be a way to associate a different price for those zones, where the price would be $0? In that case, even if they purchased the event, at $0 it would be a clear flag that they were not allowed to receive permission.
With the system we are building, there are human actions necessary through the process. After registration customers have to be put in their "occupancy" group manually (We need to make sure they are not cheating) and then they'll be able to purchase an event. After purchase, their names are entered manually and assigned to their cable or satellite company, and the eligibility is checked at that point as far as the blackout zone.
Automating this would basically save us from having to issue refunds.