I tried the AT mines trick several times, but never could get the timing down. So what I did was this. I used the Engineer class with the Explosives specialization, and equipped mines and the SAM launcher. I then placed a bunch of mines around likely choke points and near the jeeps. I then drove the skid loader past the hangers and down to the beach (on the longer arm side of the island). I then jumped out and equipped the SAM, jumping back in every minute or so to keep the loader from auto destroying. I just waited until a plane or chopper came close enough to lock-on, and fired then jumped back into the loader. The 2nd time I used this technique I got a kill with my 2nd SAM (the Apache had already been damaged by a F35). Using this techinique will amplify your chances since you still have the mines out.