All it takes is an unusual and inefficient method that requires a lot of money and coordination? I'd say that's a non-issue.
Eh, I wouldn't put it past them to go all out. Not like they're crossing the border for fun. They're escaping from miserable conditions with their sights set on a new, more prosperous life. If they're gonna make the attempt, they're gonna use every trick they can.
With that in mind, it'd be an insult to their resolve to not go all out on defense as well! Let's add minefields, unmanned attack drones, and a lava moat!