Limiting How Many Custom Monsters Spawn

I'm looking to dynamically alter the number of monsters that are spawning in the world dependent on a few different factors, however, I can't seem to find a working solution. It seems that this might be hardcoded into the game, perhaps in WorldEntitySpawner. Essentially, my goal is to have certain custom monsters be able to spawn during the day, though ideally, monsters wouldn't be as common during the day. There are also some other factors that would go into this, though they don't pertain to the issue. I've tried adding different restrictions which would either stop the entity from spawning in its canSpawnHere method or canceling a spawning event. The is only prolongs the time it takes for Minecraft to spawn what appears to be the max cap of entities that can spawn around the player (which looks like it gets set to 70 for entities of the monster type). Regardless of my checks and restrictions, eventually there will be the same amount of monsters spawned as their typically would be at night.

If anyone knows of a way to limit this that I have perhaps looked over, I would appreciate that. To me, it looks like it's hardcoded into the game, but maybe there is a way.