Besides the Jesus room...
The best pace really is to have one person on the turret, and the other three on the level right above/behind the turret. Turret person does their thing, while the others watch turret person's side and smokers off in the distance. When the tank comes, split half to the left, half to the right roofs. "Cycle" the tank or set it on fire until it dies, then repeat.
Just incase, "cycling" (this is what my friends and I call it, I don't know what it really is called) is:
The tank has a certain priority list. It targets whoever is doing the most damage to it. If someone gets downed by the tank, the downed person becomes priority one. When you cycle the tank, only one person shoots it enough to get the tank to chase them. Then someone else shoots the tank until they get chased (thus, becoming priority one) then another person shoots the tank, etc.
Or just light it on fire and run away from it (save your ammo).
You can also camp out under the ramps, which might be easier depending on who you play with.