I'm not sure about athletic tape, sometimes called Kinesio Tape (or just KT-tape) for blisters, although I've used it to immobilize some tendons in the hands and feet. Never used it on open sores, though; I'm sure there are appropriate tapes which could work.
Moisturizer, perhaps doubled with thin cotton gloves while sleeping I've known people who've done that.
This won't address the blistering or cracking, but to restore sensitivity in the fingertips when I've built up callouses, I've had good luck using an old-fashioned pumice stone. Those should be easy to find and inexpensive. Or extremely fine sandpaper, of the sort used for refinishing delicate finishes on painted surfaces I've also used.
I'll just throw this idea out here, because it might work. There are various products under the name "Super Glue" or "Crazy Glue" or the like that might be suitable for closing and strengthening small cracks. I don't think such products would poison you, much, but it's something you might look into. Possibly clear nail polish. It's possible, I suppose. I'm sure there's some research on the web about the toxicity of these products.