Obviously make it with a smaller player count, Area 99 felt like shit both because it was ugly and also because it was overpopulated.
Or have some new MP or LTM mode, that combines things from Warzone + infinite respawns until the time runs over, but be on some map that's much smaller than Rebirth. I'm sure many people will be happy about it.
The last Halloween even with the devil- Rebirth was the closest to that. People loved that mode, you had infinite respawn and no rules, apart from shooting like a maniac and grinding xp and guns.