if you don't mind a rock floor or embedding support posts in the ground, good enough is fine: the rock floor is so thick you have to have a major error before it affects your build, and the same for buried supports. Its only when placing directly on the ground with wood that you need perfection. Basic and iron chests can serve as a thick flooring as well, offering 'hidden' storage in spades while hiding the ground imperfections.

https://steamcommunity.com/sharedfiles/filedetails/?id=2775728477