The lesson from this thread is to avoid any airline departure before 8:30 a.m. or so, if you want to use DME and RAC and to realize that, even then, you'll probably need to get up much earlier than you'd want to.
Personally, I would avoid any airline departure before 11:00 a.m. With an 11:00 a.m. departure, the scheduled DME pickup would be around 8:00 a.m., so, with a 6:00 a.m. wake-up call, there's time to get ready without being rushed, check out, perhaps have a quick breakfast, and be at the DME pickup spot 15 minutes early.
Early morning flights may seem like a good idea. You get home in time to unpack, do laundry, and take care of things before returning to work and school the next day. And airlines sometimes offer the best fares on early morning flights to fill the seats despite lower demand. However, a wake-up call around 3:00 a.m. is an awful way to end any vacation.
If an early morning flight from MCO is unavoidable, one idea would be to spend the night at a hotel near the airport (such as the Sheraton Suites or the Marriott) or, better yet, in the airport (the Hyatt). Take Magical Express the evening before, and get some more sleep in the morning. You may even save some money, depending on how your room rate at your WDW resort compares to that at the airport hotel.