Hey there I have this model and realised the bottom wasn’t flat after sculpting (see red arrows).

Now I could boolean it out with a cube but it would lose it’s nice rough edging and go back to it’s base mesh edge shape.
I’ve also tried the Flatten Sculpt tool but this intersects with the mesh.
Any tips on how I could solve this (it will be for a 3d print and I need a flat bottom).
Thanks in advance.