Ok, after some thought, I think this should be simple enough. There are only 2 basic objectives one would need to achieve in order to bring some sense to this part of the film:
1. Everyone that comes in needs to have a role in THE plan (multiple plans just makes things too confusing with all that is going on....we're trying to simplify this part of the film, not make it more complicated). BUT if we manage to make it look like everyone is working together then many of them can almost stay the way they are now and the changes we make elsewhere will make it all seem like it flows as a more cohesive plan (this reduces the amount of work that needs to be done). This means that everyone has to have a reason for being there....Lando can possibly remain unexplained as he would have been the advance scout...getting the lay of the land, and then signaling Leia...this can all be assumed, so his role in the film need not change necessarily (though I would remove his knowing look to Leia when Luke gets dropped into the pit as it makes it seem like he's letting her know that he's there, like she previously didn't know).
Chewie needs to be put into a jail cell for a reason...and this is another one that possibly need not be changed. He tells Han about Luke in the film as it stands now....so if we make it look like they're all working together then the meaning changes slightly and it comes off more as Chewie telling Han "Don't do anything stupid, we've got this one.".
Leia needs to be unfreezing Han not to escape necessarily (because Chewie is still in a cell and Lando deep undercover)....but just to have him unfrozen so that when Luke shows up everyone is mobile and ready to go. Leia then gets chained to Jabba as a slave but this is just incidental and means they must improvise a bit....I would also add a shot of her signaling Luke that she's going in (this sets in motion the end game part of the plan....and is accomplished easiest when she is still in costume....before we see her sneaking over to unfreeze Han).
And 2. R2 needs to be shown trying to get up to the main throne room...(perhaps after Luke sends him a signal of sorts) and failing.....that makes it seem like the plan was for Luke to smuggle in his lightsaber in case he was searched for weapons but for him to grab it back as soon as it was clear that Jabba wouldn't be reasonable. When R2 fails to get up to the throne room that sets in motion the need for the entire sail barge fight....as at that point they would be improvising...but sort of sticking to the original plan....just in a different place and time.