The slab is bonded to the framing and I've filled the small gap at the back with drywall mud. Once this has dried, I'll give it a quick sand, then hit it once more with a thin coat of mud, then I can cut the tape and peel it off. I'll re-tape, caulk and prime the new mud, and then I can do my color cut-in. I still need to squeeze some colored thinset in the gaps on the underside and then this one is done.