Limit Workspace Permissions for User with Product Line Owner Permission

We need an ability to Limit Workspace Permissions for User with Product Line Owner Permission.

Currently "Users with access to product lines also have access to their underlying products."

Use Case:

We have a number of Product Operations Workspaces set up under each Product Line that the Owner of the Product Line does not really need visibility into. I've just set up a new Product Line Owner. This  Product Line has 10 workspaces (5 products and 5 for operations).  I was forced to give them Owner permissions to all 10 Workspaces when they only needed the 5 products. It would be great to pick and choose.

The only way to get around this is to create a workspace after they were given original Product Line owner permission. I believe new workspaces created after show up as None by default. Obviously this is not a great solution to this problem.