hey love what about letting her go to sleep with her undies on and if you are worried, put a pull up on her whilst she is asleep. That way she wont rely on the nappy, but you have a backup.
Your DD is very headstrong, I would just wait until she makes her mind up that she is going to go dry overnight. Its just finding the incentive for her that is going to appeal to her and she will be a pro!!
xxx