I had another problem now... the console say "Unable to find shaders used for the terrain engine. Please include Nature/Terrain/Diffuse shader in Graphics settings."
So your mod doesn't work for me... help
As you can see, I've created a ground texture for the mod with a runway and helipad. There is room to add roads as well - I'll see what I can come up with later. I went for a randomly-mottled background, as I wanted something with enough detail to give an impression of movement as you fly/drive over it, but not so much as to distract. Also, a random image doesn't generate the ugly aliasing shimmer patterns you can get with a regular grid pattern.
Edit: I had problems uploading the ground texture - probably because of the file size. I've changed it from 24-bit to 8-bit colour, and persuaded it to upload. You'll need to rename it as 'GroundTexture.png' for it to work - backup the original texture first.