I build my base on the north exit of spider cave to the west beach.
It is a good spot with balance between resources access, defense, and mid difficulty raid for exp farming.
I build the base on the corner green area near the beach and expanded it to the north and east to spider mine entrance.
As for base defense, actually there's nothing to worry about if you already familiar with the game mechanics. As long you're not using /exp cheat where raid level will be far beyond your MCs and base capability.