JSD - Limit Customers/Reporters to specific projects

Today, the way customer permissions work, there is no way to limit a customer existing in projects which we may not want them too..  The end impact of this is that once a customer is created in Jira, they are made available as reporters and customers  to all JSD projects.. Which is not good behaviour as in multi-helpdesk environments, it could lead to accidents.

e.g. we now need to add a public facing project. Let's call it project A. Project A will NOT use the portal, but will only accept emails from outside users. We have no way to pre-create these accounts as they will be from unknown users. This works perfectly. User sends email, gets email, all good..

The issue we have is that when this customer/reporter is created, they are added to the Customers list of that project (perfect); however, we have Projects B through F which are internal JSD projects and are known users which sync from an LDAP source and are customers. The problem we have is that the Customers that are created in Project A become available as customers/reporters in Projects B-F. This could lead to someone accidentally using the wrong user if they modify the reporter...

Our desire would be to have the users/Customers from Project A created in project and NOT in projects B-F - or have them unavailble to use as a reporter.. How can we do that?