Before I moved to Orlando, we always went in the off season and I know it is disappointing for the parks to close early. But think of it this way, with early closing, you won't be waiting in long lines in the heat. Most of the rides will be walkons. That is a choice you make with coming to the park in a non-busy time: shorter hours and shorter lines or longer hours and longer lines. If you want the late hours, you need to come in July.
Also, just a minor correction: the parks close at 6:00 PM on the dates you are going not at 5:00 PM. I checked the Disney hours for the same dates and AK closes at 5:00 PM, MK and MGM at 8:00 PM, and Epcot at 9:00 PM. So technically, Universal isn't closing terribly early at 6:00 PM. I am sure you will have a great time even with the early closing!