Camber more than the caster. My cars also serving as DD's, I was running around -1.7 degrees in the front. On lots of non-street driven vehicles (not talking about w-bodies specifically. Nobody autocrosses w-bodies) it's very common to see guys running negative 3 degrees. I sent the tail end around on my green GTP on more than one occasion. It definitely didn't understeer much and I'm a crappy driver.
More caster will help as well though, because it helps the car gain negative camber when the wheels are turned. It's why a lot of cars now have around 10 degrees of caster from the factory.