I found pastel chalk pencils at the art store. They're like regular wood pencils except the lead is pastel chalk. A brand name General's has 4 small sets or 2 large sets, plus Dickblick might have individual pencils in the open stock rack.
The lighter colors mark just fine on darker painted areas. I scribbled some of the white pencil on some Gunze aqueos flat red. It worked.
So, there's an option for raised panel lines, bullet holes, scrapes & burns, etc. I haven't decided yet if I'll use these or a gray watercolor pencil on the A-wing raised panel lines.