Replay the Namibia Zebra hunt for this. Make sure you have a 20x scope on the .300 Trailblazer.
Play the flag collecting intro and advance to the second area. Here, run NE to the hilltop to spot your first trophy. Mark it with your range finder, and then return to your starting position and climb a rock. From here, make sure you're at least 201 yards away, and make your first kill. Claim your trophy and initiate a checkpoint.
Activate Hunter's Sense and notice the green glow behind the plateau. Move in position so you can again use your range finder to mark your next trophy, and again back away until you're at least 201 yards away before shooting. Hunt one more trophy to finish the mission, then go back to mission select before repeating.
Should you miss, you can always restart or restart from checkpoint. If the first shot is too frustrating, just do the second one as there's less running involved if you restart from the first checkpoint.