A quick google turned up this reference to fog harvesting in chile. Seems to me that a simple expedient form of this approach could be constructed with some mosquito netting and a couple of hiking staffs or found limbs from nearby trees.
Since you want to be walking in you need to be light in this answer. I would think that you could carry enough mosquito netting to form a decent double layer triangle with the point downard such that your collector would funnel dropplets into a resqvoir at the point of the triangle. With some cordage you could hang this from nearby vegetation or other liberated limbs if there are no trees on the ridge.

Let us all know what works!