Joseph,
I’m not a Posek. I am not a woman and I have not read any of the tznius “how to” books that are on the shelves in the stores to be all that familiar with all the specifics. However, it was stated here, several times by a number of people that “some amount” of hair may be exposed at least according to some poskim. Also, “how to cover their hair” covers the actual covering. Sheitel, sheitel with a little hat on top, snood, tichel, you get the point.