While I found some approaches here in the forum I still miss a complete and approved solution. So if someone has done this already would you like to share your solution here? I really would appreciate this. Thanks very much.
In the public-services-security-context.xml file you could probably change some value's. I've never tried personally other than only allowing the admin to create site's. For your circumstance around line 885-… of the file might be a possibility.
Were you ever able to get an approved solution to this? I am looking for the 'correct' way to do so as well. If so, please post here. It would be much appreciated!