Wow, Dick, being the ultimate Leadbelly nurd, this is REALLY news to me! I've seen the picture of huddie playing (probably) Bess Lomax's Martin 000, with a commercial slide bar, but a DOBRO !!?! Where's the picture? What album? Can you print it?
He played quite a number of slide pieces on his lap ("Packin' Trunk" is my favourite) and you know, he was original, fast as lightning, and didn't sound like anything I've heard before or since. The differences between his style and others (Like The Black Ace, Cliff Carlisle or Darby and Tarlton) who played lap guitar, are subtle, but they are there.
Maybe he met one of the Hawaiian guitarists like Sol Hoopie during a New York stop. Geez, what I'd give to have seen him live....heck I'd trade Catspaw's right arm for that chance!