We do the walk all of the time, takes about 20 minutes & is quite enjoyable as there are very few people. To lessen the stress a bit, I'd probably situate myself nearer to the exit in DHS to get a bit ahead of the crowd coming out. The back exit at Epcot shouldn't be that bad at that time of night, but in case you are looking to avoid the crowds, you can also stand on the bridge between Beach Club & Boardwalk to watch the Epcot fireworks. It is a nice view from there, you just don't get to see the full lake show.