Raised the ground 1 "square" all the way around since ground is indestructible, and then dug a moat behind it, both at max levels allowed. Then I placed a stone wall 3 pieces wide that has ballista installations on top of it. This way the base is practically impregnable and my ballistas don't shoot out of ammo on deer and hogs. Expensive, but its the best I know to do short of building out an island like I did in my second world. Stakes just slow them down and drain resources with needed repairs. Also, the entrances can be built in a way so that enemies will not be able to navigate. The real trick is keeping the creatures out of my harbor area.