Frankly, Thorsim, I think you're trying to make way more out of it than you need to.
This isn't a scenario. It's an ever-changing FSO.
Making side-specific forums is only going to make things more difficult, make already-change-resistant people want to NOT change sides, and frankly it's a bit pretentious of the FSO event as a whole to pretend it really needs private forums.
I'm not saying it's perfect. There are bumps in the road now and then. Overall, however, it has survived for how many years now without private side-specific forums?
IMO, just like asking for no icons, "private forums" is just another way of making it like the AvA arena (as in during the "war" they have). We don't want that.