Hi, glad you are making progress, I was worried because with all the camber heathen's is more of a Loose setup and you had been driving Stable so good for you, Loose is faster. Sorry, I think you are stuck with the tire temps because of the track.
I would guess you could be closing the radiator to 20%, where are you now? Changing the ride height would give you more speed down the straight than reducing the radiator opening under 20%.
On the Engine symbol the middle number will show damage from overheating, over 20% after a couple(EDIT: sorry about 5 laps) laps will mean the opening is too small.
Radiator change from 20% to 10% improvement is 0.100.
Ride Height change from heathen's to 105/100 rear improvement is 0.200.