CMSimpleCoAuthors is a CMSimple solution with CMSimpleCoAuthors (CMS, based on CMSimple, with some new features) and the CMSimple plugin CoAuthors.
External authors can create own contents in an own installation of CMSimpleCoAuthors, installed in a subfolder of a CMSimple installation.
The administrator of the public website can insert that contents, using the plugin CoAuthors, into the public website.
Please visit the Project Website for more information:
http://cmsimple.org/en/?CMSimpleCoAuthors