Rv'ing and the New Immigration Laws

What do the new immigration laws in the west mean for those who wander about in a vehicle?  The Supreme Court just upheld the portion of the AZ law that requires the police to check for papers proving that a person is legally in the US.  They noted that police must not racially profile to determine this and they must have some reasonable suspicion that a person is possibly an illegal alien.  It seems like the two are pretty much inconsistent.  How do you suspect that someone is illegal if you don't racially profile?  If they have an accent?  Would a cop in AZ consider a heavy New England accent to be foreign?  I've heard some so thick I could barely understand them.  Same for some southern accents.  Even particular places in Maryland have very different accents.