I would propose a modification to this plan. It seems like most of the bandits are drunk, so now is a good time to attack, definitely. However, we know that some of the bandits are going to leave soon. So, we wait until the group is walking away, then have Alaira and Darius sneak as close as they can, then suddenly attack the few that are remaining. If there are any archers still. Ssarak can fly up and crush their faces. We would time this attack so that the others leaving can hear some commotion behind them and turn around. If we're fast enough on the initial attack, we can hide, then proceed with your plan, but on fewer enemies at once. 

Alternatively, we can wait until the group that leaves is out of earshot, take out the ones in camp, then catch up to and attack the others with your plan.