Is it possible to have a content and a portal admin

A customer would like to have contentAdmins, who should have the right to 
add and edit the content on a page, but should not have the right to add 
pages to the menu or main-navigation on the left side. Only the 
portalAdmins should have the right to setup the portal structure.

I have given the portalAdmin and the contentAdmin WRITE Rights on the 
Startpage, and on the navigation container-list, I have taken away the 
WRITE rights for the contentAdmin. When the portalAdmin creates a new 
page, this page inherits the ACL from the parent ContainerList and not 
from the parent Page. So the WRITE Rights for contentAdmin always have to 
be explicitly set for every new page. 

Another way I can think of solveing the requiremtn is setting the rights 
in a Jahia event handler. This would still give the customer the 
possibility to change the Rights configuration, if he wants to override.

A third possibility is to add a hardcoded check in the template using 
JahiaUser.isMemberOfGroup to decide, whether the admin menu for navigation 
lists should be displayed. This would be rigid and would not allow to 
customize the behaviour via the Jahia GUI.

Is there an other better way to solve the requirement?

Greetings,
Benjamin