See Don't call a doctor for more info on Siege Mode.
For this map there isn't any one place that is good for camping, but there is a glitch that allows you to exit outside the map's playable area which allows you to complete the map without worry of failure. One of you should get outside the map and the other stays inside to kill off all the enemies. The person outside should focus on not dying.
Here is how you get outside the map:
First go to the underground tunnel, and along the right side there are some rocks. You must work your way up these rocks, on top of the tunnel, then to the other side outside the map.
1 - Go along the right side of the rock, jump up into the corner, slide along the front of the rock and get onto the top.
2 - Get on top of this rock and then walk back a bit, then sprint jump to the next rock, rock 3.
3 - Just simply jump up to the top of this rock.
4 - This rock is actually invisible, so you have to get onto it to where you are able to see the top of the tunnel, face the rock wall (not the tunnel wall) and move right then back to the left really fast and spam . This should land you on the top of the tunnel and then outside the map.
The weapons that are unlocked on this map are:
Wave 5 - CQB.45
Wave 10 - TAVOR
Wave 15 - MINIMI