This really could be a game. You have to sort out who you let in and who you keep out. And there be penalties for what ever way you go. Their can be the law abiding migrants with papers that your supposed to let in. Their can be the guys that sneak in with no papers, your supposed to stop them, but half the populace gets mad at you if you do. Others can be guys that sneak with drugs and guns, You still make half the population mad if you keep them out, but they do damage to the country if you let them in and you make the other half mad. Then sometimes you get a mob charging in and throwing rocks at you. If you stop them, you get half mad populace and bad press. Let them in, other half gets mad and random effects will happen.
Although now it sounds like a game you can't win in a satisfying way.