I was thinking of suggesting she play with the companionway stairs, pots & pans, the main sheet, knots, the steering wheel etc.. but I didn't know how that would go over.
My girls always wanted to do what the big people were doing. That might be why your daughter wants to play with all the sailing equipment. Give her a job, and give her lots of attention. Second choice would be to let her bring a friend, but at that age you'll probably need to bring the friend's parents too.
Never listen to someone describe why your project will not work unless they can show you the broken pieces of their own version. - Robert Gainer