If you estimate 3 hours per park, that's 12 hours, plus travel time so we'll assume maybe an hour or so eaten up in travel time. 12 hours would be like 9 AM to 9 PM, so you could probably even make it 4 hours per park (on average...so perhaps 5 at Magic Kingdom and 3 at Animal Kingdom), for a total of 16 hours. So if you factor in an hour to travel, that would be 17 hours. But that would be like 9 AM to 2 AM and the only way that would be possible would be to make it on a Magic Kingdom EMH night when MK would normally close at 11 and is open until 2 AM for EMH guests.
Problem is, since most of your attractions that you want to do are at MK, I would suggest doing that park FIRST...get there when it first opens and hit all the attractions quick. Perhaps even go on morning EMH day for Magic Kingdom. Get there at 8 AM, quickly knock out everything you can during that hour, and for anything that might not participate in morning EMH, do it last, after 9 AM. Theoretically, you could have those 9 things at MK done in an hour or two, then high tale it to the next park and so on.
But if you're really serious about wanting to do this, you need to strategically plan it based on park hours. For example, if Animal Kingdom closes at 6 PM that day, you naturally don't want to plan to make that park your last stop. So maybe do it right after Magic Kingdom (if you do decide to do MK first for the reasons I gave). Or maybe do Animal Kingdom first, on AK morning EMH day. Then rush over to Magic Kingdom. Either way, since Animal Kingdom always closes around 6 PM at the latest (except on EMH night, when it may be open till 9 or so), I wouldn't plan on making this park the last stop under any circumstance, even evening EMH.
I've never tried it, but as I think about it, I would think that certain conditions would have to be present in order for this to be "doable". If you're talking about a peak time, then I don't see how it could be possible. The first park, sure...before all the crowds arrive. But once the crowds come and the fastpasses start backing up, every ride you might want to do at a park may have huge lines and fastpass return times several hours away. I would think that this would only be doable if you go during a time of year when you can have relatively easy access to the rides.
Another option would be to go on that one day during the week (usually Monday, I think) when there are two parks doing EMH: Animal Kingdom for AM and Hollywood Studios for PM. That way, you can start at 8 AM at AK, knock out everything you want to do there, do MK and Epcot (in whichever order, probably MK first since you have more there to do) and then close the day out with evening EMH at DHS.
But I would strongly suggest taking advantage of morning EMH at whichever park you want to do first because, it seems to me that you can get alot more done in that one hour before the park opens than you can in the 3 hours after a park closes. During AM EMH, you beat all the sleepy heads to the park and have it to yourself for an hour. But during evening EMH, you're there with massive throngs of people who are wide awake and ready to spend more time in the park. I've been at Epcot before for evening EMH and was able to walk right onto such rides as Maelstrom, Grand Fiesta, Living with the Land and Nemo, but when it comes to Soarin', Test Track and Mission Space, forget it.
Sorry if I rambled too much and you fell asleep reading my long post. But I just wanted to throw a few thoughts out there on how to execute this plan. But like I said, I would suggest either doing MK first on morning EMH day, or finding the day that has a morning EMH for one park and an evening EMH for another (and this only happens on one day of the week) in order to maximize your time and take the best advantage of a dead park.