I wouldn't have a problem with it if it was for building inspection and processing facilities on Mexican soil. That way we wouldn't have to deport the people who get caught.
It would seem we already subsidize Mexico to an unseemly degree. Welfare on a grotesque scale. I don't agree that it is appropriate to blur the lines in this way, on the allegedly pragmatic grounds of prophylactic action.
Clearly Mexico, as one of the richest nations on the planet... has all the resources they need right now to do whatever is necessary to staunch illegal border excursions by their own illegally migrating populace of have-nots....sanctioned and abetted by their governments.
All of them. Past, present, and undoubtedly future. They will gladly set up 'make-work'infrastructure on their side of the border, with our money. But what it will actually do will only be like W's virtual fence, only be a cosmetic window-dressing...a pretext for the continued non-enforcement which is the actual marching order of the millenium. It will give the Mexican government a thin cover under which it can continue a pretense of cooperation.