I didn't get 20 (yet), I am still on 2K18 and found an effective solution for myself. I don't really focus on realism, because to me realism is an illusion.
I look for a challenge that requires elements of strategy.
Try these, very challenging:
Default the User sliders to all
50
Increase all CPU attributes to
60
Exceptions:
Durability- decrease to 35 for User/CPU
Stamina- increase to 52 for User/CPU
Fatigue Rate- 57 (both User/CPU)
If you find this too easy, or too hard - tweak to your liking. Maybe drop the User sliders to 48 or even 45. I use these for MyLeague and it works wonders. Whatever you set the CPU attribute sliders to, like for instance 60, I will correlate this with the MyLeague "Simulator Difficulty" slider to 60 as well so it reflects my difficulty.