I think I have figured it out why the Red Bull is so
much faster than the McLaren. Noticed how much closer
the front wing of Vettle's Red Bull is closer to
the track than Hamilton's McLaren. Vettle on the right
and Hamilton on the left.

The down force one gets from  a wing in ground effect is
an exponential function of the stagnation pressure point distance
above the surface. The down force to drag ratio is also improved
I suspect. At the time I felt the exponent was the cube or greater.
I noticed this back in the late 1960's on the Chaparral nose while
measuring down force as a function of speed and  mentioned it in
my paper:

Aerodynamics & The Group Seven Racing Car by Paul Lamar
Presented at the AIAA Symposium on The Aerodynamics
of Sports & Competition Automobiles
(Research I did while at Chaparral Cars.)
April 20 1968

http://www.rotaryeng.net/AIAA-Paper.pdf

While both cars are stationary in the pits the legal distance
is the same. This can be achieved mechanically by using
a internal spring in the front compression strut. As soon
as significant down force is applied that spring bottoms
out.

To make something more subtle coaxial components made from
different composite materials could be used to tailor
the force verses the deflection function of the front compression strut.
One component can be cured and pre stressed while the second
component is laid up enclosing the pre stressed component.
These components can be no more sophisticated than carbon and glass
due to a huge difference in the modules of elasticity.

Paul Lamar