You need to use different repos for this kind of segmentation, regardless of any introducer flags or not. The full list of nodes sharing a repo is always sent in the connection handshake; the new introducer flags only affect what the receiving side does with this information.
However if ultimate privacy isn’t what you mean with “see ONLY”, then all you need to do is configure your network as above and not set any introducer flags, just as it has been in earlier versions.