If you're just worried about running out of things to do and getting bored, don't worry about that. True 2 days is generally enough time to do both parks, but we take a week at the resort and a 3rd day is a good amount of time to go back and re-ride the stuff you liked on the 1st and 2nd days. But sorry don't have an answer to your specific question, I am assuming you can do that though. We usually buy the 7 day tickets.