Structure Stretching Down (Feature Request)

What this would do, exactly, is in the structure element menu, it is an option that could be checked, would be like how village houses used to generate. If a village house tried to spawn on the side of a hill, it would copy the bottom layer all the way down until all blocks in the layer are touching a block that is not air/plants/other non-solid blocks.

And how this would be useful in mods, if someone was to make a structure that is on stilts, like a hut, and the structure spawns on a hill, it won't look bad because the option stretched the stilts down to the ground.

Please add this! :)