Instead of repainting sat_lco I am using the aerial photo and altering it to fit the map - necessary since ArmA roads are constrained to 10 degree rotational increments and real roads are not. Plus one needs to eliminate tree and buildings and their shadows, paint the roads for long distance visibility, etc.
I use the Project | Export Map as image tool, then convert the EMF file to PNG and import that as a layer into your paint program.
By turning vegetation, roads, and man-made objects on or off and exporting them, you can create multiple layers in your graphics editor and use them as a guide to retouching the sat_lco image.
The point about the roads is that you cannot make the roads in V3 follow real world roads exactly because the engine is limited to a rotation of 10 degrees. This is especially bothersome when the real road is straight as an arrow but not at the perfect angle for V3. So if you want to follow the real world road your V3 road is going to have a lot of zigs and zags to keep it close to the original. Then you have to repaint the sat map image because at mid to long range the road objects are not drawn by the program. Instead the player only sees the sat map image. If you don't paint the roads on the sat map they will simply disappear a few hundred meters away. This is especially noticeable on open terrain and when flying over your map.