I think, you are thinking too complicated.
a) why Multitiki for that? No need.
b) why Apache settings and such? no need
=> just point 2 domains (or more if you like) all to the same Tiki root directory
=> got to tiki-admin.php (provided you have setup your categories and perspectives etc) and choose 'Admin' -> 'General' -> Tab 'Navigation' -> scroll down 'Multidomain
Here set "domain2" to the appropriate perspective Id
Should be about like this:
no entry for the default domain, where you want to see everything.
I have no time to explain everything right now (need to make food ;-) ) - but try this first please and then come back for further instructions