Thanks, everyone!
I have only been soaking her for a half hour, so tomorrow I will try one more soak and try it twice as long and see if that will get that last bit off. It's just been very frustrating. And from her point of view, I can only assume that a slab of dead skin clinging to your body has got to be so obnoxious. I see her crawling all over her driftwood pieces, but it just won't budge.