Airport hi-res overlay file

[NickB]

I found it is possible to use a hi-res overlay bitmap/dds for an airport at up to 16384 pixels, but it gets mixed with the default asphalt.dds file and makes the runway too dark. It can also be used with the default asphaltpaint.dds and because it is mostly white it works quite well, but the cracks are a little too large and a little too pronounced. I tried using a 'white' local asphalt.dds or asphaltpaint.dds in the same folder as the overlay, but it doesn't get used. The use of the airport_muck.dds is quite good to provide darkening and coloring of the asphalt and asphaltpaint, but for an even more realistic looking runway with all its flaws, an overlay is better. Is there a way to use a 'white' file to mix in the overlay somehow ? Or perhaps use a suffix, much like ' airport_muck.dds' but 'airport_overlay.dds' or 'airport_ovl.dds' so that no mixing occurs ?
I have attached a screen capture that shows clockwise, texture dds 4096x4096 only, with asphalt only, with asphalt mixed with overlay, and asphaltpaint mixed with overlay.