Im trying to reduce the number of NPCs that spawn in the wasteland. Not the respawn rate but the amount of NPCs. — I find the wasteland too busy.

Ideally i'd like to reduce the chance of a spawn in a leveled list but there doesnt seem to be a way to do that. (i.e. 75% chance that nothing will spawn)

I tried removing creatures from leveled lists at lower levels but the game requires at least something in the list or else it crashes to desktop.

Any ideas?
My current solution is to replace most criters in leveled lists with Brahman, which needless to say is not ideal. (Could i add a blank npc? Or is there a bird or something less noticeable then a brahman?)