As a slight concession to the difficulty of the track, I'll just leave the track grip at 100% the whole time.
People will have to be aware that drivers ahead may be backing off the pace to survive the race, so be prepared for cars being slow into corners. It will be all too easy to punt someone into a fence and potentially wreck their race.
I've only done a 8:33 myself, but I've opted for reasonably high downforce, to keep the car on the track for safety's sake. You can easily do the distance on 1 tank, but I haven't seen how the tyres fare over the distance yet.