After you blast the blackhawk in to little tiny pieces, there will be two camps you are ordered to clear out. The first one is west of the blackhawks position, and is the only one of signifigance here. There will be a truck parked near the building in this camp that definitely counts as a secondary objective. There will also be three vehicles that approach the hacienda after you have secured Rosen. I don\'t believe that these are secondary objectives. However, if you take them down, you will be greatly benifiting yourself by limiting the number of enemies that you have to fight. It would also be the safe thing to do.