Originally posted by Mick:

Started exploring some burial chambers on the second land mass took my raft to in this game. I figured that after I clear it of all the Skeletons, then I can build my next base inside or at least refurnish the place with a worktable and cot.

Is this possible?

Unfortunately no. Which is understandable, the interiors don't exist on the regular map, and enemies can't come or go from them.

What you CAN do though is dig out under a boss platform (such as the Elder) and make your base there, which isn't quite the same thing but still fun.