The set near Closeburn that we pictured in 'The Search for Middle-earth' has drawn a number of guesses. Several people have said 'The hill of Seeing.' Here is what Joe Piela had to say:
"My first guess would be Cirith Ungol: when I first saw the statues they reminded me of the two watchers (though their location up high rules against it), and that sword you noted looks like an orc scimitar. So I would guess the stuntmen would be Shagrat and Gorbag's orcs fighting amongst themselves. My second guess would be that they are REALLY spice up the "Hill of Seeing" scene (after all you noted that the thing on the raised platform looked like a seat or throne), with the Orcs first attacking Boromir up on the hilltop right after the confrontation with Frodo. That way they can start the carnage early and have Boromir leave a trail of bodies down the hill"
Now I LIKE that! I'm convinced!