Actually, viewing by the Pirates of Caribbean on the Rivers of America is one of the prime viewing areas for the fireworks. So when you finish dinner, hang around the front of POTC for Fantasmic, and as soon as that is over, stay in the same area as the people start to leave, and fireworks will start (weather permitting) and you'll get a pretty darn good view with less crowds. the only thing missing are the castle projections/lighting and some of the fireworks that come off the castle, but you get most of the show there.