I would not chance it. DME pick up is 3 hours prior to flight times for a reason - too many things can be delayed or go awry.
In the best case scenario - lets say you check in a little early, are seated on time and then rush through dinner, finishing around 5pm. By the time you walk all the way to the front of the park, exit, walk to CR, wait on the Uber - its 5:15-5:30. Its then a 30 minute commute to the airport - 5:45, 6pm maybe. If this is a weekday, it can easily be longer than that because of construction and rush hour. Being that its an evening flight, I would expect security to be particularly busy, especially if its a weekend. Airline boarding will generally begin 30 minutes prior, and if you happen to be flying Southwest, you'll want to be there when boarding starts to board with your position.
I suppose its technically possible, but I would not count on everything to be that smoothly and timely. There are too many variables out of your control. I know I wouldn't want to end my vacation rushing through an expensive meal and running Home Alone style through MCO.