My base is pretty ugly in comparison to some of these but it has worked so far. Just a little moat (just needs to be chest high on a troll basically), and a stone wall. In my case it's on the ocean so things can swim up but honestly it's not that big a deal. There are some things that will be able to get over the moat, but for the most part it's held up and I'm on the last biome now.

https://steamcommunity.com/sharedfiles/filedetails/?id=2669622763