You'll be there for a whole week. Just take one of those days and "camp out" early. No need to see it every night. And try to see a late show instead of the early one.
Here's an idea I've not seen: instead of standing and waiting like everyone else, squueze your way through NOS to Critter Country before the first Fantasmic!. Have a fastpass or two each for Splash. Go on a few times. during Fantasmic!. For pure torture, you can try the Pooh attraction, if only to have experienced it to criticize it. You can also get a bite at Hungry Bear. I think it's open during the show, but I don't think you can see well from there.
So, after the first show, everyone is making their way out of NOS and toward the Hub for fireworks. Now's your chance to stake a good Fantasmic! spot right on the rail.