Hi again:
Looks like that will be an interesting project for you.
I'll bet that there is a significant "pilot's pucker-factor" taking off (or landing) on either KEKO RWYs 12 or 30 with a full load on a hot day with a strong, gusting, headwind ...at nearly a 1-mile ASL Altitude !
FYI: I am assuming you are familiar with the fact that AI traffic will only work on perfectly flat and level surfaces in FS, ADE RWYs are, as intended by the author, "perfectly flat and level surfaces", and thus do not work on sloped RWYs.
However, a "sloped flatten" terrain polygon
can be made in ADE (and other scenery utilities such as SBuilderX); simply set the Altitude for each vertex individually along the course of the polygon edge.
This "sloped flatten" terrain polygon will over-ride the local terrain mesh and give you a standard FS default terrain surface which is of course, already "hardened".
This terrain surface can then be textured by default or custom land class textures, including FS SDK Resample custom photo-real aerial imagery of that location (which technically is a 'special' form of land class).
BTW: If instead you make a copy of the existing surface of your 3D model as a separate 3D entity, and successfully make that the "platform" with a 'hardened' concrete attribute which is super-imposed over- and attached to- the top of your KEKO RWYs 12-30 main 3D model, you need not make a sloped flatten below the sloped RWY area, as once the top surface has been successfully 'hardened', it should prevent user aircraft from "falling through" the terrain surface.
Hope this helps a bit more !
GaryGB