Secure install base for secured customers

We have a business case, where our client also does projects and services for some secured/govt/defence customers. When they create an install base and link customer location, they want only cleared personnel to view these assets information. We know we cannot have data masking on production env, and thus we were thinking on creating a seperate maintenance organization and all the install base for such customers are to be linked with that special org and give data access for the secured personnel. Was wondering if anyone else had that requirement and if there is a better solution available? Also they