Hmm, RSS… that is a little complicated. Also another implication I did not think of is the activity stream. If the idea is to restrict access to content, then both the RSS, the activity stream (and the activity stream RSS) have to be considered.
Before we go down the route of considering another plugin, have you already tried this one?
Description Installation Screenshots Other Notes Changelog Stats
Author: Rodney Blevins & Marius Ooms
The BuddyPress Groupblog plugin extends the group functionality by enabling each group to have a single blog associated with it. Group members are automatically added to the blog and will have blog roles as set by the groupblog admin settings.
Full blog theme integration. The included bp-groupblog theme mimics the group pages.
WP Admin option to set default blog for groups plus bonus options.
Automated blog registration at group creation stage.
Bypass default blog validation to allow dashes, underscores, numeral only and minimum character count.
Blog privacy settings are initially inherited from group privacy settings.
Group members are automatically added to the blog.
Blog roles match group roles as set by the group admin.
Solid error checking that the blog follows validation.
Group admin tab to access the group-blog settings.
Recent posts are displayed on the group home page, much like the forum topics.
A menu tab is added to display the latest blog activity and blog page links.
Blog themes will have the ability to pull in group info and create a theme that could resemble the group exactly.
Leaving the group will downgrade the member role to ‘subscriber’.
Allow the group admin to select one of his/her existing blogs.
Known Issues: * Group blog post do currently not show up in the group activity stream. Therefore as a short term solution we are including a custom activity loop on the blog page. This should be fixed in the future.
Allow the admin to let group admins choose the blog name, instead of following the group name.
Frontend posting from the blog home page.
Redirect options to integrate deeper with the blog.
Include an RSS icon for easy access to the Blog’s RSS feed.