Unless the mist is down there are no navigational problems. You are walking along a ridge with a wall running along the top. For a vast majority of the way you can see the valleys at each side of you. So, basically, having attained the summit wall you merely follow it along the top of the ridge to beyond Cosh. Even before the trig point at Horse Head you can the whole of your route ahead quite clearly.
You can also see (again assuming that them isn't isn't down) the slopes of Plover Hill once the bulk of Darnbrook Fell is out of the line of sight.
The footpath due west from Kettlewell is initially clear and then has places where it becomes indistinct. However, there are no problems just heading the short distance upwards to the wall.
The bridleway to through Moor farm and the one which meets it and ascends the ridge is also easy to follow. It passes through the summit wall at a gap so all tracks head for this point
Rhodesy's route is also easy to follow although a tad longer. Don't worry about navigation though for, if the weather is clear it is a doddle. If it is bad, I should stick to a lower alternative.