Darth Piccolo said:
I'd rather have the boba/plans plot remain anominous so the audience caould figure it out for themselves rather than sponfed like lucas's prequels. that's why my idea of showing boba leaving jabba's palace and later his ship is seen leaving one of the rebel ships would work better.

It might work either way.

The tell through showing approach would be labour intensive so perhaps your approach could be phase one and other people could build upon it if they feel the final effect is too ambiguous.

TMBTM said :

EDIT: so I agree with Darth Piccolo. No Vader calls to Fett would be even smarter. It would make the audience think that the rebels have a chance. Until Palaptine says that it is in fact a trap, at the end of the movie. At that moment only the audience understand that Fett was working for the Empire.

I'm never convinced that the trap is much of a surprise anyway (especially after ESB), surely the surprise is that they still manage to win regardless.

Like Hitchcock said you have to show the audience the bomb to draw tension from it.