To stay completely covered in mud for any length of time once you have left the swamp is not realistic, 10 yards of walking through leather leaf will scrape all that mud off. Also once the mud dries it falls off easily. I seem to end up pretty muddy pretty often, for some reason, but it is usually on the outside of my clothes. I suspect the indians used mud alot but probably also washed off frequently in the rivers. Also, I am not a historian on Lenape tribes in the pine barrens, but I recall reading that few tribes actually resided in the barrens permenently.
Jeff