I'd suggest you telling us to all sit at a spot - then go spawn all the mobs for a wave.. then tell us we can go fight - rather then trying to spawn them while we go.. I just feel it'd be more fun if we had to fight the whole group at once.
Also you could make sneak in a few baby bosses and such just for fun.. or maybe even harder ones like Berr.. or ant queen or ventus or bonesaw! (I actually don't recommend the ant queen.. or even really ventus/bonesaw haha but hey you said we can die:P).
If you get a crowd like today I don't see any reason not to go a little crazy with how many you spawn..