if your park passes cover pleasure Island, you could eat there. I believe they have a cs that's open pretty late. At least they did back a few years ago. I was also planning on going to MGM the same night as you, but am now thinking of reconsidering. I tried getting an ADR for one of the TS restaraunts in MGM and was told they were completely booked. So I'm guessing MGM may be quite crowded that night.