Bettik, Dead_Cell, Single Ds, and myself just got 12.21 on the last stand portion of survival mode. Basically, if you go to the bedroom where they are writing about derrick and line up on the wall you can watch each side the door and the window. They break out all of the walls to the right and in the bathroom but its ok because youll be against the wall. More importantly than anything is setting up the room and the other rooms for the assault. You can pick up a pipe bomb and then walk in the room youll be at and replace the moli on the floor with the pipe bomb, this is essential because youll need many pipe bombs for when you need to get HP and when you need to get supplies. Then take all the gas cans and propane tanks and line them up in the other room so that you dont blow or burn yourself to death. Make sure everyone has shotguns as this will prove important in bringing down the infected and other tanks. Start it, get in the room grab hp when needed using pipebombs and watch each others backs, there are a ton of infected and the hunters knockback seems to be more. anyways we did this 3 times. first time was just 12:00, the 2nd attempt was a massacre and the 3rd was 12:21. heres the screenshot and bettik has a video of the strat... oh yeah at 6 min marker you get 2 tanks, need to be setup for that.