Just My .02...
This will be our third MNSSHP and if you hit MK on the 29th...- we'll be coming in. Last year, they started to let ticketholders in at 4:30 PM - before park closing for day guests at 6.
My choice would be to do another park that day- only because I couldn't stand for MK to be closed to me at night! MK at night is one of my favorites in all the World!!!!!