Airfield background grass textures

I have designed and added several airfields to FS9 using a combination of AFCAD and FSSC . adding runways , taxiways and comms details with AFCAD and buildings macros with FSSC is not a problem. However one problem is the background.
If I use AFCAD or FSSC to produce a polygon and colour it with a texture, that texture remains un affected by seasonal changes.
If I look a some airfields that Microsoft have deleted (eg's RAF Machrahinish and RAF West Freugh in Scotland (both supposedly Black ops sites ( Halo Aurora etc ) , they use a grass background texture that is subdued and it changes with season and gets covered in snow.
I have been reduced to using fixed textures or superimposing the runways etc over the existing textures. This latter is especially a problem when using grass runways as the airfield does not stand out from the air.
Any suggestions anyone?
If I use AFCAD or FSSC to produce a polygon and colour it with a texture, that texture remains un affected by seasonal changes.
If I look a some airfields that Microsoft have deleted (eg's RAF Machrahinish and RAF West Freugh in Scotland (both supposedly Black ops sites ( Halo Aurora etc ) , they use a grass background texture that is subdued and it changes with season and gets covered in snow.
I have been reduced to using fixed textures or superimposing the runways etc over the existing textures. This latter is especially a problem when using grass runways as the airfield does not stand out from the air.
Any suggestions anyone?