I think there is not really a good solution for my
described "problems"
available, because mediawiki is not designed for access-restriction I
aim to (using access-restricted sub-wikis by specific teams).
You hit the nail on the head. The only way to implement access restrictions
across multiple wikis in MediaWiki is to install a second copy of MediaWiki
or to configure MediaWiki to connect to a completly separate set of database
tables. The later is preferred (managing one software base is easier than
two) and can be done by hacking LocalSettings.php to apply the correct
settings depending on $_SERVER variables, using the SiteConfiguration class,
or using Farmer (
http://www.mediawiki.org/wiki/User:IndyGreg/Farmer).
And if you are enticed by all the patches out there claiming to do access
restrictions, don't bother. Many other extensions (not the access
restrictions ones) use direct database queries to access article information
and because of this, bypass any security measures you may have in place.
Bottom line is MediaWiki is designed for all or nothing access. If you want
more control, use different wiki software.
Greg