Excuse me: I'm going to exit this post and make a new post showing how 2 cores and 2 expansions can make a 9-player Rune Age. I gotta go to work. The forum is now Tony P.'s on how to make a basic core and expansion fit more than 4 players. Be back with an update in an upcoming post. Again, sorry for the brain storming mess.
I doubt I'll ever get to play a five player or more game so its kind of a mute point to me! I hope that works out well!