I think it is only racial profiling if you use the stereotype observed in law enforcement or to take similar action. I would think that having observed in random sweeps that a high percentage of day laborers do are undocumented, ICE agents could concentrate on day laborers among other sources in their searces.

Are you asking this as a legal question or a moral one?

Legally, in some states, you are required to check the immigration status. In all states I believe you are legally required to report the employment and submit with holdings and taxes. Morally, it depends on how you feel about illegal immigration.

Have you looked into calling a temp agency an trying to hire two guys who have papers? Alternately How about high school kids? In Columbus GA, Where I lived for a few years. I saw lots of day laborers whose ancestry was certainly African. But they were probably citizens. It is probably a matter of looking a little harder.