I've had some pretty large bases, and they have all been sealed off with walls and moats. Never had an issue with a mob spawning inside of a base. 30+ mods installed.

To answer the original question, anything that comes into contact (including players) will be injured by stake walls. You can place them around your walls to keep the smaller enemies from attacking the walls themselves. I like to put some in the moats to kill the ones that fall in.