How to restrict smart form purchases by deliver-to locations AND specific users

Summary: Need to restrict smart form purchases to specific users AND specific list of deliver-to locations.

Content (please ensure you mask any confidential information):

Customer requires a specific smart form to be restricted to selected users. We managed this using content zone restricted to worker. However, for this specific smart form, delivers must always be shipped to a specific address/deliver-to location. I have confirmed content zones do not allow access to be restricted by both worker AND deliver-to location.

We recommended customer uses SSP Preferences to default the deliver-to location, but they do not feel this is acceptable as they essentially will have a centralized group of users who raise PR's on behalf of many different departments (and therefore deliver-to locations). They do not want to have to update preferences every time they create a new PR.