It's difficult to get dynamic hair to be thick enough to cover the scalp without bogging down your system.

You'll notice that dynamic hair that comes with Poser 6 uses textured skullcaps, as a sort of cheat. 

I often use 3Dream's textured skullcaps.  Not to grow hair on - they are too high-res - but afterward, to cover any bald spots.

That won't work with monk-style hair, though - you need the bare scalp for that.  The only thing I can suggest is to increase the hair density and strand thickness until you get the coverage you need.  You won't need many vertices for a hairstyle like this, so you can make the hair denser.

If you haven't downloaded Kirwyn's free Genesis hair, do so.  It's a great tutorial for dynamic hair.  (He uses two skullcaps to get the needed thickness.)