As a general rule, mid summer is a good time to decide where you are going to plant. This year is somewhat exceptional because of all the rain we've had. Typically, those barren spots will not be good for ginseng. It might well grow there, but slowly if at all. I would look for a happy medium between the really thick spots and the open ones. Sometimes, the best course of action is to go in with a mower and some glyphosate (Roundup is the most expensive and most recognized) to kill off what is left after mowing. I normally go through and remove any valuable or companion type plants before going to this extreme.
This is why I recommend smaller test plots. Do a small 200-500 seed experiment in both areas and see what works for you. You might find as I suspect, ginseng will grow in both extremes, but each will have their own issues.