Perhaps a way to do GA would be to just restrict the groups. This would still effectively reduce the number of teams, so less work.
One could also give non Meta groups bonuses to prop them up. Frex:
Wretched Hive: Scoundrels, tusken and Jawas ( tusken and Jawas get 3x health and power)
Balance: sith and Jedi only
To remove the need to move mods you would need to not announce the bonuses before roster lock. The ideal solution would be to lock rosters a few days ahead and announce the bonuses then. This would give people time to thing about it and hype the event a bit.