Here's something to think about. A good stretch of the border between the U.S. And Mexico runs down the middle of the Rio Grande. Where would the wall be built ?
In one local town the wall would be between the city and it's waterworks department. Mostly between the landowner and the rest of his property. Between the nearest access road and every boat ramp. Between the highway and the restaurant on the river.
Oh, and don't worry about the restaurant. Their boat dock will be full with customers coming across from the South and all the US employees can be replaced from Mexico as well.
The "Wall of Stupidity" will provide lots of jobs so folk can then run down to the QuickStop and send money orders back to their family in Mexico and Guatemala.
Maybe the most efficient foreign aid in US history.