He'll fail too. You can't help but not to. That's not a crack on his editing skills, but the Prequels, by nature, are designed to take the "surprise" element away from the revelation. I mean, you can try and chop up Ben's speech in the hut to Luke, but you're just going to hamstring that particular scene, which is one of the 3 or 4 most important scenes in the WHOLE SAGA actually, especially in terms of tone and acting. To take a scalpel to that just so that the twist in Episode V is maintained is throwing baby out with the bathwater. And again, that's really the only way you can make "preserving the twist" work. Don't worry about Episode III, you gotta figure a way to re-edit EPISODE IV and not cock that sequence up. And since the whole POINT of that sequence is to educate Luke about his father and use his father's legacy to lure Luke into joining the Jedi, you can't really chop any of that out without totally kneecapping the dramatic drive of the WHOLE MOVIE at that point.

Plus, untangling all the birth/death crosscutting in the final act of Episode III is just a mess. I guarantee the flow would end up choppy as hell.

I don't understand why it's such a big deal to "preserve the secret" anyway. Again, the best way to do that is just show whoever it is you're planning on showing these to, in their theatrical release order. And even then, there's no guarantee they won't already know. That twist is such pop culture trivia at this point I know people who have NEVER seen Star Wars and know that Vader is Luke's dad. The movies seem to stand up just fine without the "oh SHIT!" factor in V, and editing Episode III to regain that seems futile. You won't get it back. It was lost in 1980. And besides, that twist isn't really the point of the movies, it's not the fulcrum the whole balances on. It's a very important point, yes, but the movies work whether or not you're actually SURPRISED by the announcement.