Not a rollercoaster.

Stable Porsche 992 GT3 R Setup for Bathurst / Mount Panorama - Assetto Corsa Competizione.

Note: Negative toe might still work in the qualifying environment. But all my setups will for now utilize positive or only slightly negative toe as I expect it to be the more sustainable solution.

The Porsche just feels great with a balanced race setup. Ever so slightly willing to rotate on entry, stable in the middle off throttle and again willing to just mildly rotate on exit (apart from high speed, where its pushing a bit). It might be best simulation ACC has to offer. Everything feels really round and smooth, no excessive behavior in any situation.

Overall the new Porsche needs less steering as before and it's easy to turn too much. The high steer ratio helps to be precise.
Be careful on turn in. The tires likely need half a turn or more to build temperature on the surface and they are more snappy on entry when still cold. You can get them warm more equally by reducing camber and going for more positive toe. This will cost lap time in general, but might gain you time if the car is unrealiable on corner entries for you. While the car remains the crazy rotation off throttle, the center of that rotation seems far more in the center of the car now, than around the tip of the nose, which makes it rotate more like a mid engine car. The rear doesn't feel quite as exposed on corner entry, and you get actually turn into the direction you want to go, instead of controlling a permanent slide. In Q the weight balance is still very far to the rear, hard to do anything about it. I tamed it as much as I could and again no negative toe needed here for (most of the) lap time.

Bathurst / Mount Panorama
Bathurst is tricky for many reasons. Long straights ask for good acceleration and lower drag, yet the high speed corners on the mountain need 'rotation' and the direction changes down hill require stability. The track is asking a lot and I hope I found a good middle ground: Not quite max wing, not the most imaginable rake, allowing the car to duck on the straight, yet not make it bottom out anywhere else, while remaining predictable in all driving situations. Braking in Q is trickier than in race trim, due to the missing weight on the front and maybe you want even lower brake bias than I used. You will experience shorter braking distances in race trim. In Q the brake bias is further to the rear to stop the front from locking up. The behavior changes quite a bit from Q to Race here. And you can still go higher with brake bias than me. 
Especially in the race it feels very balanced and despite the wear difference, it remained stable as far as I got into the stint. The race set definitely starts on the understeery side, but it will certainly become more oversteery as the weight balance changes and the rear tires outwear the fronts. I tried to give the front a chance to lift up as the fuel tank empties, reducing the front bite from downforce to counter the weight change. Let me know if this is getting you through a 1h stint, or if we need to add more changes. 

Driving

• Aim for late apexes and dont shy away from a short shift or staying in the higher gear option in the first place
• your brake is more than a means of deceleration, it also controls pitch and especially in Q this will be key to managing rotation on corner entry - most pronounced in T2-4, but also the slow corners, like the hairpin, need careful trailing to not lock the front tires
• on throttle the car will keep rotating, dont just floor it as that might exaggerate it - take a close look at my throttle traces, especially at the exit of T1, T2 and Audi Corner (T4). Position is key here. Use TC3 if needed, but 2 provides faster laps in Q and if you feel like it, switch to TC1 on exits if you can manage it.
• dont steer too much, progress into it, be ready to steer neutral on exits.
• The fast corners up the hill will all be flat - just a tiny lift over the crest for the last left to make the front go for the corner
• Stay on throttle over skyline. The car isn't that fast there and there's still plenty of space to brake - the throttle will further stabilize the car and especially in race trim its almost flat where other cars need a full lift or even jump

Adjustments

• If too oversteery: Stiffer front spring (this will lead to more oversteer later in the stint, try the other options first), stiffer front roll bar, less rake. One click at a time.
• The brake bias is tricky. If it's too far forward the front will suddenly regain grip and the rear snaps. If too far back the rears might lock. Higher ABS here if you cannot handle it, but likely at a time loss. Clean trailing will pay off.
• higher preload can give more turn in stability, but will come with more nervous exits
• lowering front and adding rear camber might further stabilize the car (in race)
• lowering the caster also gives more predictability
• Some drivers might like a car with less rake for better drivability. It does not seem to be too problematic to lower the wing in turn for 2-3mm lower rear ride height.
• rear tire wear remains an issue. Lower camber all around the car might help paired with more positive rear toe - but its just something you can't fully control.

Tire pressures
Aim for 27.0 entering the fast corners for solid support from the tire without surprises. You can play with the fronts at lower pressures, so they develop some temperature. Yet we have a lot of high load corners here and a stiff tire feels much more communicative than a soft one.

Lap times
Q fuel: 15L (This is safe to use for the sprint races adding the necessary fuel of 48L - maybe add 1 click of rear ride height)
R: 110L (including formation lap)

LFM: For the shorter LFM races you'll likely be best advised with the Q set and a bit of fuel, less front pressures, but without any other changes.