Legit 100% Gamerscore completionist.
Me and a few buddies did this today using your basic srategy, although I'm not sure if they found it here or discovered it on their own. It is pretty much the ONLY way to do this map for vidmaster though. One spotter with laser, one guy on a chopper, and 2 guys runnin the hog.
We ended with 1,690,000 points and could have gone MUCH further as we still had ~20 lives when we reached the 5th set but two of us absolutely HAD to leave once we got the achievment for real life issues.
My two cents for this achievement is the following: ANY group of 4 SOLID (and I stress solid) players should be able to easily attain this achievement on platoon. We had the good fortune of having an absolutely OUTSTANDING Chopper driver. He is a beast in those things, and was a great asset. Not to mention our Hog driver can dodge like Whoa.
At any rate, this achievment just takes patience. I tried it with one other group. Epic fail. This group did it our first try and had like I said ~20 lives left when we got the achievement so it's well within the reach of seasoned players. If you are a seasoned vet, seek out your brethren and don't let this achievement intimidate you because it's really not all that hard on platoon with the hog, splaser guy, chopper guy strategy.