Unlike Illuminations, Epcot Forever has a ton of high fireworks, so seeing it from outside the park may not be so bad. We wished we were there for a day longer since it's debut was our last night there so we watched it from in the park, but we used to love watching the high fireworks from Illuminations from the pool at YC/BC, and we wished we had an extra night to check out the view from there for Epcot Forever since the fireworks were so much higher for this show!
As for places to watch, the bridge between Epcot and Boardwalk as mentioned before would be good, I would even recommend the beach in front of the BC. Really the show is mostly the high fireworks, the lower ones are just spinners by the water so it's not a big deal to miss those.