Sorry to rain on your planned out-of-court negotiations.
My take is that your divorce will end any real control you have over your wife. When she has custody of your daughter, you will not be able to control Watchtower influence, just as your wife will not be able to control how you educate your daughter when you have custody. Verbal and written agreements to the contrary will end up being futile. Your daughter will quickly find out that you are evil association and are bound for destruction at Armageddon whether you like it or not.
Divorce plays into her hand; since if the unbeliever departs, she is not bound to remain single. I can envision your wife getting remarried to a faithful Jehovah's Witness who will also support your wife and make sure your daughter is educated in all things JW.
Is there any chance of you sticking it out, for your daughter's sake?