I don't think the "Wall" folks are as adamant about the wall as you think. I, for one, would be quite pleased to see that money spent on tracking and registration, esp. in re: employers and SSN verification.
I'm sure that someone will immediately post behind me about how important the wall is.
I just noticed I was posting pretty much the same thing after you. The anti-illegal immigration folks aren't as wall-obsessed as this guy likes to believe. Any enforcement mechanism will do as long as it isn't tied to amnesty.