I got a coop from the thesmartchickencoop.com specifically so I could DLM in the coop. No floor and predator proof. You can take a look at their coops for ideas.
Have you tried this yet? How has it worked for you? I would think the bokashi bran or spray would need an anaerobic environment to work properly, which is what we definitely don’t want in a chicken run. I’m not sure how you’d control the type of mold that would start to grow in the layers if no...