There is a post earlier in thread, I followed that and it went perfectly. It is all about smoke. Airstrike the first wave of guys, then smoke and run to the hut on the left handside of the field. It should checkpoint when you get in the hut, it took a few seconds for mine to activate. Then put an airstrike on the fence(roughly), smoke by the fence, run to the fence, smoke again so it lands by the road barrier, smoke again so it lands over the barrier, run over the barrier and down into the house. Once in the house I had a straight run to the bottom of the hill. I hid in the petrol station for a minute then just ran into the helicopter once it came. Using this method I found it a lot easier.