From reding others reports, it seems that the MK will close to capacity at some point during the day. We are arriving on the 4th and going to Epcot....handles large crowds better and we want to see the special Illuminations.
We are only focusing on the fireworks, not planning on standing in line for rides or having a TS meal. We will grab something to eat CS and ust chill out until time to get a spot for the show. We have 7 more full days for the rides.
From what I have read the MK does the 4th's fireworks show on the 3rd also, so you could see it then if you will be there on the 3rd and then go to another show on the 4th. Many people suggested watching the fireworks from outside a park on the 4th.
We are going to brave Illuminations inside the park and just take our time getting out of the park.