We ended up with 80+ enemies fighting 7 players and 11 NPCs.
I had a co-dm who played the commander of the enemies. He decided what they were doing and when they were doing it. He rolled all the dice. I determined the results of those dice and directed the encounter, managed the HP pools and initiative.
It was exhausting, not going to lie. We played for 6 hours and only did about 5 rounds all up.
In the video below I show how I prepared the encounter files in Realm Works and managed the bulk initiative and handling of HP pools for all the enemies.