The S-class events are very challenging on pro physics. The most practical suggestion would be to use standard physics, as it's fairly evident that the races were tuned with that in mind.
If you prefer to beat all challenges on pro physics, you'll be in for quite a challenge, and you'll likely be mostly on your own, since most players (even here) did S-class under standard physics.
Personally, after passing C-B-A with the same settings as you, and spending a bit of time on S class with standard physics, I switched to standard to blitz through them. I'm currently working on getting gold on all events, and then I'll go back and try them on pro physics.