For me, this is where I use my wracks. I use them for screening, if needed, and against 3 units of Alpha Legion Berzerkers, you need it! Just keep in mind that they get to attack twice, that means that they get a 3" Consolidate move and another 3" pile in move, 2nd attack and then another 3" consolidate move. So you'll need to be at MINIMUM 7" behind the wracks to avoid that 2nd round of CC. At 7"-9" the Berzerkers will still be in range to consolidate into you to "tie you into CC"
If the deployment map prevents you from being 10" away, and forces you to get in the 7-9" range behind your wracks, then you have a couple of options:
1) Just make sure that the units have the fly keyword
2) Make sure that it is a unit of Grots or Blob of Wyches. If he consolidates into them, you get to attack, otherwise they will be hung out in the open to be shot up.
Also, they will very likely want to use the Fury of Khorne strat, so make sure to throw out AoV on that one.
After that, use your speed to get away. Oblits I wouldn't worry about as much. You'll need to weather a round of shooting from them, but that's usually doable. I usually use the Lightning Fast Reactions strategem when a key vehicle (Ravagers) are targeted by the Oblits. Keep the Ravagers alive and they will make short work of them in your next shooting phase. Even if your Ravagers get destroyed, blasters work in a pinch to take out or at least thin the Oblit numbers. You can also use the Torment Grenade strat to help you kill the unit if needed.
Everything else, you'll have the tools to deal with.