Don't forget to build a LOT of powerplants for the fence. And hope the illegals don't hire an electrician.
Both of you have it all wrong!!!
All you have to do is set up a few watchtowers... string up some barbed wire fences, which could be just a single strand of barbed wire... and contract out 20 or 30 military contractors (which could very well hire illegal aliens) to put in land mines.