Prior to writing my last post I did think about the last scene is ESB and even watched it. Lando says "When we find Jabba the Hutt and that bounty hunter we'll contact you" and didn't mention Tatooine that was enough for me and I must have zoned out.
Oh well that answers my question. That probably indicates at least the direction of where the story was heading in '79. And considering the deleted scene from SW in George's mind Jabba was on Tatooine.