Or we could do as Mexico does :
1. ANY citizen can place ANY suspected illegal immigrant under arrest.
2. If the citizen is wrong, they CANNOT be prosecuted for the false arrest.
3. Illegal immigration into Mexico is a felony.
Also, if we taxed all monies being wired out of the USA to any country south of our borders at a 75% rate, the profit motive evaporates and illegal immigration stops the next day.
Truly, it is possible to force Mexico and other countries to pay for the border wall. We simply lack the will to do so.