I just looked around the web a little bit but was unable to find a good Bluegrassy version of it written out anywhere. There may be one out there, I just didn’t find a good one. I notice John here on BGD hasn’t done a lesson on this yet. Perhaps you could ask for one by him. I’ll bet anything he does a super job playing this one.
I play it in a bunch of keys but seem to like it best in the key of A on the fiddle because of the drone notes.
I just took a break on “Are You Washed” in the key of G and then followed it by one in the key of A. These breaks may help to give you some ideas on how you could improvise. You can always slow this video down even two speeds if necessary and get an idea. Hope it helps.