What do you need help with?

I have an underground build that I want to do. The base it self is sounded by air blocks because I want pretty much anything to be allowed to occupy that space. Is there a way to do this with baritone? I've looked and there doesn't seem to be any thing I could find in the documents but I might just be wrong. Obviously I want it to be able to hollow, so ignore all air wouldn't work. Is there a work around for this? Is it best to just fill the exterior with dirt? This is for survival so resource management is a factor.
UwU

Final checklist

• I know how to properly use check boxes
• I have not used any OwO's or UwU's in this issue.

Not yet possible.
I think instead of filling the exterior with dirt you can take a schematic of the desired location, merge it with your base schematic in a creative world and then let Baritone build the combined version, which contains exactly the surrounding blocks that are already there.