Perhaps it would be better to protest by refusing to patronize businesses known to hire illegals?
Great thought, but then you would have to stop buying fruits and vegetables (who picks them?), meat (who works in the packing plants?),no hotel stays (who cleans the rooms?), no buying a house (who built it?)
The list would go on, but you get the idea. There would be little to boycott in the retail world.
In that case, I will turn my head when I drive by a construction site.