A couple of things...
First, if you want to stay at the MK until close (12am), you would get back to your resort around 12:30-1:00 am. So, with that in mind, you would need to give DME the flight info for a flight that departs MCO around 3:30-4:30am...and that will be difficult.
Second, I believe your resort guest "privileges" only extend until midnight on your checkout day. Therefore, you would have to utilize the DME return before midnight. That will make it even more difficult to find a "dummy" flight that departs between 2-3am.
I would think that under your plan, a town car service would be the best, or do as a PP suggested and call DME directly and explain what you are looking to do. They will be able to give you the definitive answer.