You have so many options. This is my thought. PTN at Small World will start at 8:50 and clear Fantasy Faire Gifts by about 9:10 pm. If you are watching from the Fantasy Faire Gifts area, you can take the brick pathway behind the trees. If you are sitting on the other side, or farther down, you'll have to wait until the end of the parade reaches the teacups before you can enter Fantasyland. If it takes you 5-25 min to get through Fantasyland to Frontierland, you'll be stuck because the lights around Rivers of America will be dimmed (haha) until Fantasmic is over at 9:32. At 9:35 it gets dark again for fireworks which end around 9:50 pm.
Below is a map of the Small World area. The blue lines indicate how they rope off a walkway in the middle. The red is the brick pathway that I was referring to. If you sit in the teal or yellow areas, you can exit via that pathway.
If you stay to watch fireworks at Small World. At 9:50, you can cut through Fantasyland, and Frontierland should be mostly clear of the first show guests by the time you arrive (although, there will be others like you entering). You will need to get to Harbour Galley to enter your Fantasmic viewing area. If I recall correctly, they start walking guests to the seating area for the second show around 10 am. Second show is not as crowded as the first so it is likely, but not guaranteed, that you will be towards the front.
You can also flip it and do the first Fantasmic show and second PTN. For the first Fantasmic show, they start walking guests down to the dining package area around 7:45 pm. A line usually starts to form around 7-7:30pm. If you want to be guaranteed against the rail, I would head over to Harbour Galley early. Watch Fantasmic and fireworks from ROA. At 9:50, you can exit via Adventureland with everyone else and meet up with the crowds on Main Street then swim upstream against the crowds leaving Small World fireworks. CM will allow those exiting Small World to go straight towards Main Street. They divert those walking towards Small World to the right (towards Tommorrowland) just before the Matterhorn. Granted it was July 4, but we were caught in that mess last night. If you are diverted to the right, you need to walk around Matterhorn and enter the Small World area by Edelweiss Snacks. Or... you might find a place to watch the second PTN on Main Street or before you reach Small World.
You could leave Fantasmic through Bayou Country, try to catch the 10:15 Shadows of Memory (10 min long) and then leave SWGE via Fantasyland to get to Small World. The second PTN starts at Main Street at 10:50. We were sitting in the Small World queue area (the very end of the parade route) for the second show last night. The parade arrived at that area at 11:15 pm.
