Thank you all for your responses!
Basically, it sounds like that though the Boardwalk is just a short walk away from the WS, unless you are staying at an Epcot resort, you really can't just walk out of Epcot after Illuminations over to the Boardwalk. I guess you need to walk all the way out of the front of Epcot and drive your car over to the Boardwalk. What a pain in the butt.
What about another strategy? Do buses run between the TTC to the Boardwalk (or even the Epcot resorts) late in the evening? Could we just in the morning park in the MK/TTC parking lot, take the monorail over to Epcot, and then late that night take a bus from the Boardwalk to the TTC to be re-united with our car? Does this sound do-able?
Thanks!!