First off to get this done, without any hassle at all, everyone will have to have the most beastly technician build they can get
Insane Skill Power is the key. You will be depending on the Sticky Bomb along with the First Aid skill. Added to everything will be Triage Talent, which will speed everything up and make the experience a lot smoother and faster at that.
Sticky Bombs: You will need the Technician skill to be as high as possible for maximum damage, because they are the only weapons that will work for the glitch, normal bullets won’t take affect. Also, you must shoot the Sticky Bombs under the vehicle to even make a dent. P.s. Stick together so your Triage/First Aid Skill/Talents take effect.
First Aid : You will need first aid to get Triage to work, it will also increase the damage to your sticky bomb.
Triage : You want this partnered with First Aid for the fastest experience for the glitch, It will cut cool-down time by a lot, especially with a group of four, which you will need.
But before you are able to get to work, you all must get through the glitch, the window, you can not trigger the mission or you will have to fight all the NPC’s and you will feel the bullets from the mounted turrets. The trick here is to run at the window while spamming the shield button ( you will have to equip the shield for this part) so it warps to the outside and leaps you over. Once done you can all get to work and claim your rewards once you are done. That is basically it, but even though it might seem easy, it is a lot longer, then it would take doing it the legit way, the only difference is that this way is 100% guaranteed to be beaten, because you will not be killed at Wave 11 or if anything goes wrong, because nothing will go wrong. Enjoy.