A lot of people turn their music either right down or off and the HUD effect off when attempting Zone Zeus, as both are a distraction.
It's best to attempt getting it in 1 hour blocks, then give it a rest, do something else for about 20 minutes, then have another shot at it.

It's frustrating, but you'll get there, just try to do as many perfect laps as you can, which sounds obvious, but that's exactly what needs to be done.

Well since you have already remapped your air brakes and have hit a dead end, maybe try mapping your air brakes back to L2R2 just for this [I'm pretty sure that's what I did as you don't need to touch any other controls when attempting it], there is finer control with L2R2, but like a lot of others I don't like using the default for normal racing.