You can alsouse liquitex matte super heavy gel, it's usually used for impasto techniques and retains brush strokes really well. If you do use liquitex paints, the heavy body paints themselves retain their brush strokes well when used straight out of the tube.
My worry would be the flexibility of the coat. Personally, I'd reccomend doing most of your hair flat and then going over a few strands with your thick paint to enhance the light areas for dimension. If you build up a lot of texture there is the possibility of it wearing down or flaking off in the future. Of course, the longevity of your paint depends on the mediums you use, but that is always something to consider.