Hi David550xi,
I'm using the Logitech G923 as well and as you had to fiddle and tweak with the settings to make the cars contollable. I've found that so far the below settings work best for me:
All deadzone insides are set to 0 except decelaration, that's set to 5.
Steering and acceleration and decelaration deadzones outside are set to 80.
Clutch deadzone outside is set to 70.
Vibration scale = 40
Force Feedback Scale = 100
Aligning Torque = 150
Mechanical Trail = 100
Pneumatic Trail = 120
Road Feel Scale = 80
Load Sensitivity = 100
Wheel Damper Scale = 100
Center Spring Scale = 20
Dynamic Damper Behavior = 50
Wheel Rotation Angle = 460
Steering Linearity = 45
I hope these settings will work for you as well, or at the very least give you a solid starting point to tweak to your personal preferance.