Putting aside that you're going during one of the busiest weeks of the year...
Personally, I'd take the money you're spending at Narcoose and see if you can get a dessert party reservation instead. That will ensure you have excellent viewing, without being jammed in or shuffling to find a spot among the horde. I haven't searched the board to others' experience, but our experience viewing the fireworks from Narcoose is that it's, eh... ok, but you'll likely be disappointed. You won't be able to see much from inside, so everyone goes out on the porch. You're at a distance and an odd angle, so your view of the fireworks is off a good bit. What's more, the viewing deck is not much different of a view than the boat landing, which the price for it is included with your stay

. Meanwhile, the viewing location (get the terrace GREEN party option) for the Wishes dessert party is the best, full stop (from someone who's seen the show probably 30 times from all over the park. If you can't get a dessert party, if you can get anywhere near the front rail or back of the walkway behind the viewing area early, you'll have a good view. For my money, the food is not worth the price at Narcoose, and the view isn't worth it either.
DPT: if you can't get a reservation, call dining reservations an hour before the party begins to see if there are any openings. Occasionally, people cancel at the last minute and you can pick up the vacancy. Have gotten lucky this way twice now. Just be standing near a guest relations building when you do, so you can walk right in and get your confirmation, which you will need since they probably won't have your name on the check in sheet at the terrace.