I have two followups, a tape beg and a tangential piece of metadata.
First, does anyone have a copy of the Elvin Bishop set, with Jerry sitting in? Apparently there is an aud tape of it.
Second, at http://www.dead.net/show/june-4-1978 commenter jacksondownunder writes
I caught the soundcheck the day before [i.e., 6/3/78]. As I wandered up to the side gate the band was jamming a long instrumental "Dancin'" riff. They eventually stopped and Bobby & Jerry started playing the melody of an old Harry Belafonte song called "Yellow Bird" on twin slide guitars. (I recognized the tune, having heard it on my parent's records hundreds of times.) Then the band started jamming a riff that at the time I presumed was an instrumental vamp of Feat's "Dixie Chicken" (plausible), which is listed above as Iko (possible), but as it followed another Harry Belafonte song it coulda been "Women Smarter" (probable). The half dozen of us kindred strangers made the mistake of applauding and were chased off.The writer thinks "Women Smarter" more likely, but I am going to go with Iko Iko, which had entered the Dead's rotation in 1977. That's speculative, caveat emptor.
I don't recall that info being in Deadlists, or if that entered the Deadbase 50 updates, but it should be a bit more firmly on the record than I recall it being.
A list of known soundchecks would be fun to see.