Remove protection of a child of protected page

[Myster]

It would be nice to have some pages unprotected on an extranet style website, eg the register page, the about us page etc.
even if the homepage is protected.
as per: https://our.umbraco.com/forum/core/general/49452-How-to-remove-protection-of-a-child-of-protected-page

One way to implement this, not sure if it's the best way, could be... assign a group to anonymous users, then we could grant access to members of that group who wish to visit the register page.