The funny thing is that it's already running quite a bit of camber, and the tire misc screen doesn't show any sign of the tires "turning over"... which is why I'm reluctant to add more. I also don't want to compromise straight line braking, as that's another problem area for this car. I will give it a shot, though.
I wouldn't call -0.8 a lot, unless you're drag racing. I know I run more camber than many people out there, but my milder cars are -1.0, and I've got some with as much as -1.4!
Try to find a balance that heats the tires at the same differential front and rear, then add/remove 0.2 degrees and test out to see where you find the most grip.
I probably didn't explain this phenomenon well... The oversteer only comes when I upset the car by lifting when cornering or hitting rumble strips. Through chicanes and on entry it understeers quite badly (and abruptly, there's little warning), although sometimes it feels like all four tires are losing it. After a bit further analysis it's actually quite good on power exits.
Rumble strips I would ignore when tuning for handling balance; they'll upset your car more than any adjustment could possibly correct.
If you get lift-throttle oversteer, there's two good ways to fix it: with the suspension or with the diffs. (You might also be feeling the effects of toe, but thankfully you're running zero toe.) The complication is that with AWD, you can control a LOT of the car's transitional behavior with the diffs. So you might end up masking poor damping with your diffs, or vice versa.
To reduce lift-throttle oversteer with your dampers, you need to slow the weight transfer to the front. Do so by stiffening your rear rebound damper and/or your front bump damper. I suggest starting with the rebound damper, as playing with your bump dampers will affect the wheel's initial response to a bump (like a rumble strip).
To reduce lift-throttle oversteer with your diffs, tighten up the rear decel diff. It's rare to use a decel diff setting tighter than your accel setting, but for illustration purposes try setting your rear decel to a crazy-high 80%. Your diff should lock up under even mild speed differences under deceleration, making the rear wheels refuse to turn at a different rate, and preventing your car from turning much.
After playing around, try to find a setting that makes the car tuck in a bit without that dangerous lurch to the apex you often get with an open rear decel diff. Also be aware that the differential between your front and rear diffs will affect cornering balance. Again I'd suggest opening the front decel diff to 0%, and adjust the rear by itself.
I don't have any Skylines, but I have a ton of Subarus and a few Porsches and other AWD cars. When I first test drive a car, if the diffs don't feel good off the bat I set them to my most frequently-used settings:
Front: 30 / 0
Rear: 60 / 20
Center 80% rear
I almost always tweak from there depending on the car... most often the rear accel to keep neutral under throttle, and rear decel to tweak turn-in response. But this is a good starting point for my driving style.
