Public / Private Solutions and Forums

As an alternative to using SSO for managing user sign up and the admin tasks that creates. I would like to manage what users can see. I can do this in solutions by using the company filter as we have control over this on the user. So only users assigned to a company can see selected solutions. This works well for solutions that are only visible to one or two customers but for the knowledge base area which we allow all customers access it is time consuming to add every company and then maintain this going forward. What would be good would be to be able to select all companies or exclude users with no company. This would also be required on the forums , once company restriction has been added in this area. We also need to be alerted that a new user has signed up and then assess whether it is a member of the public or a customer. A filter on the user enquiry screen would also be very useful as we have had to tag each user to enable us to drill quickly to users in a specific company.