Or you could just leave a hole in the middle, make several levels and put a bonefire in the center on the ground floor, here an example:
https://steamcommunity.com/sharedfiles/filedetails/?id=2649704384
https://steamcommunity.com/sharedfiles/filedetails/?id=2649703931
https://steamcommunity.com/sharedfiles/filedetails/?id=2649704075
(i didn't fully decorate it out at the time, as you can see...)