Like Vermon360 I also used a second controller and the same map (Urban), I just found it to be the easiest map to deal with. I set my match up a little different though. I set the round limit to 3, the time limit to 5, and the starting CR to at least 10,000. I just bought the Superdragon and used its grenades. I found this path and method to be the quickest and easiest to destroy the items... I started with the boxes at the "Shrine Gardens" (3 grenades), then to the "Red Light District" (6 grenades), then "Factory St." (1 demo kit), then "Shipping Co." (3 demo kits), and finally "Flyover" (1 grenade).
The achievement should unlock after 3 matches if you destroy all the items in each round. Oh, and you should also move the "second" player once each round or it will end the match early, I found this out the hard way and needed to play a quick 4th match.