My DH and I have done all 4 parks in one day several times. You can fit quite a few things in at each park if you decide before hand exactly what you'd like to do. If you are doing all 4 parks in one day, it is much easier to do if you are eating QS exclusively, or maybe only one TS. TS can be very time consuming and that certainly works against you when trying to do all 4 parks in one day. We always eat QS exclusively but when we are doing all 4 parks we try to eat only food that we can walk around and eat. It saves so much time! Also, when we do all 4 in one day, we try to put a park in between Epcot and MK. We spend the most amount of time at those two, so our all 4 days run smoother when we don't do Epcot and MK back to back.
We are also NOT morning people, so we don't start our days early either. This is our schedule from one of the times we did all 4 parks in one day.
We started the day at AK at 10am. We had breakfast in the hotel so we didn't have to worry about food for awhile. We lucked out and only waited a few minutes to ride EE. Then we watched the 11am Finding Nemo. After Nemo, we drove to Epcot. We got to Epcot about 12:30pm and walked to the WS. On our way to WS we got a FP(still paper) for Mission Space. We each got a sandwich from Les Halles Boulangerie & Patisserie while we walked through the rest of WS. After our sandwich we rode Maelstrom. We each got a treat from Kringla Bakeri and headed to FW to ride the Seas w/ Nemo and Mission Space. We left after Mission Space and drove to HS. I don't remember the exact time we got to HS but I know it was around 4:30-4:45pm because we watched the last B&tB, which is usually at 5:30. We got a FP for ToT and watched Beauty and the Beast while we waited for our FP time. After B&tB we watched the Muppets and VotLM. Somewhere in between Muppets and VotLM we got a chicken sandwich from Backlot Express. At this point we decided to go to MK and we were standing on Main Street by 8:30pm. We spent the rest of the night at MK, which was open until 1am that night.
I recommend eating during the concert, instead of waiting for Wishes. If you're eating at 1pm, you are bound to be hungry before 10pm. Epcot world showcase has lots of great places you can grab a sandwich or hearty snack and eat while you watch the concert. Sommerfest in Germany has a very filling Frankfurter with sauerkraut, or w/o if you prefer, that my DH says is WAY better than Casey's. Les Halles Boulangerie & Patisserie have very good, large baguette sandwiches or my personal favorite are their ham & cheese croissant. They also have several delicious desserts. If you eat food you can hold during the concert you and your mother won't be absolutely starving by the time you're watching Wishes. If you want to eat during Wishes, Sleepy Hollow have delicious, and quite filling, waffle sandwiches.
