Watch the Walt's Cooking Chords online guitar lesson by Matthieu Brandt from Modern Mountain Banjo: Clawhammer & Up-Picking
This is a typical melodic clawhammer song in open G, so DGBD with pedal G. In the first part, the harmony is implied by playing melodies that target specific chord tones. In the second part, we're adding melodies up the neck, again around chord tones. And the third part uses melodies within full chord shapes, adding or removing fingers to keep the harmony going, while you're playing the melody.
As a bonus, I'm throwing in quarter triplets to create some rhythmic tension and I'm using a technique I picked up from Walt Koken. He'll use kind of a sloppy right hand together with double stops on top of a pedal bass note. Check it out!