If the mill is the only concern,then just pour an equipment pad.
You should be able to support and undercut each post in order to pour a footing without removing the building.
You could then pour the slab. You would need to pump the concrete.
This is it. The dehumidifier you want is 800+
There is a concentrate they sell at hd you mix with bleach and water. Hose all the wood down for the mold.
I'm closing on a house next month and I'll be doing the same thing.
I got some of the encapsulation tarps cheap from a deal on here. It's...