The drive train needs a minimum travel to be flexible but you can never design it to be compliant because the surface changes so much in the span of a run and from one run to another.
The required geometry changes were all done with modifications to stock parts.
I limited my cars to about 1 inch total.
Modern cars have a lot of work done by the OEM for aero stuff and will have a device under the front bumper already.
I sorta preferred to lower the car to almost scrape the ground and with a slight tail up angle to let more air out than in.
Added front air dams have a use ,but for my application they made the front of the car larger.