Before Billions of borrowed dollars are thrown at a proposed solution, it should be asked if the Billions of dollars are actually buying anything useful or if it is just buying Billions of dollars worth of self-delusion.
A physical fence is as useful as building a fence around your property to keep flies from coming to the garbage cans filled with tasty food that you have left open. If you build a 20 foot-high fence, the flies simply fly 21 feet and one inch off the ground and fly over it.
YouTube Video: Look how fast illegal aliens can pass over, under and through the Border Fence
In the State of Georgia, right now, illegal aliens are deporting themselves out of Georgia because of the recent Georgia law that targets the closing of attractions that brought the illegals to Georgia.
Illegal aliens are self-deporting from Georgia
Georgia's solution (put the garbage can lid on the garbage can if you don't want flies buzzing around your back yard) is a much cheaper solution and, most importantly, a much more effective solution than this:
If I were designing the wall it would be a double wall with manned gun towers and shoot to kill orders against those trying to violate or sovereignty.