We fly down from Portland too!
As for entering stadium, I believe they open the gates at 11am for the afternoon games.
I'd definitely fly in the night before and leave the morning after the game. WAY too much stress to try and get to LAX after the game. Just enjoy yourself and hanging out with the fans. Its my son and my favorite place to be, we'd hate to rush any of it. Not to mention, you pay a lot to fly down and see a game, get a room for that night and you'll enjoy it even more.
I'll be at that game too!