You can adjust settings, and I do, but once you clear an area if you stay near the area the options are either “randomly spawn in zombies where you’ve cleared” (ignoring whether a zombie could actually path there or not, last I tested it) or “no more zombies”. There’s no built in way I know of to simulate a glob coming in from the edges of your safe zone if the edges are farther out than the limit of cells it simulates around you.

I could probably get something together with the horde night mod. Just haven’t had time to tinker lately.