I tried something that no one has mentioned here yet. I put the AI on -7 with Hard tires.
What this does is give you the big Montero rally truck right in front of you, the Gathers Drider Civic in front of that, and then 3 other cars. On the front straight, you pass the Montero and Civic before you turn in. But then there's a big gap between the next cars. This allows you to turn in tight to the apex, and keep it tight while the 3 slower cars exit and swing wide. Then you power past them before T1.
This automatically lowered my T1 time on the first lap from 17.2-17.4 to a consistent 17.0, and I'm sure there are a few tenths remaining.
I could never get the AI to cooperate on -10 and RSH's. I always ran into someone. This makes them easier to pass and there's barely any risk of contact.