Like a lot of capture-the-base missions, this one is very easy to achieve an A Rank on. For this particular strategy, you will require a tank equipped with the Construction Arm. Place a single Fencer in Area 3, slot B, and immediately deploy them to kill Shmarder. This should consume 2 CP. Once he has been silenced, use your tank to rebuild the bridge in Area 4 and clear any enemies from the camp so that a Scout/Engineer/Someone can run across the bridge and claim the camp. With the tank positioned inside the camp beforehand it can retreat for 0 CP.