If you look into the schedules on Disney's web site, it is possible to stand in Epcot, see the MGM fireworks over to one side, just before the Epcot fireworks start. Then leg-it onto the mono-rail back to Magic Kingdom, to see the Fireworks and the late spectro-magic parade. We did this on a Saturday in July last year. Marvellous. (We parked in magic kingdom car-park and got to Epcot around 8pm.)