In survival mode - last stand, in the back of the house there will be 2 rocks.

Jump on the rocks and slowly walk off but look down and there will be a piece of land.

When you walk off pull back on the analog stick and you should land on the small piece of land.

Make sure you have a sniper to shoot the smokers because if you don't pay attention they can still get you.

Make sure you're kneeling and the tank cannot get you, but if you wait for 20 minuets the tank will find a way.