I’m not saying I’m sold on the idea yet, but you can fit Fett’s call between Jabba’s sentence and the arrival at the Pit of Carkoon. Reedit the bit where Fett uses his rope to capture Luke to make it seem like he’s trying to capture him alive, then Vader’s arrival (to an empty Palace) can come after the departure from Tatooine.

It might screw with the pacing, but I think it’s worth an attempt to see how it works. If new footage can be shot and lines can be recorded that don’t sound like bad impressionists, anyway.