Possible to limit CAD Doc user access based on document category attribute?

I am investigating removing access to Creo Parametric drawings for some users, regardless of state, and still give them access to assemblies and CAD parts. I was thinking the Document Category attribute could be used but it isn't available in the policy, which can only be configured by domain, context, type, state and participant. Could I somehow create a CAD Doc sub-type that are only drawings? I also looked at profiles to hide them but didn't see a way to use it for this purpose. Other ideas?