Non Skid

Never tried it, but just thinking out loud, I've seen some sandpaper (Tamiya I think) that has very thin backing paper and is very fine grit. Perhaps something like that glued in place and painted the proper color?

Not too long ago I saw a model of a WW II US destroyer and the builder had used decals to represent the non skid surfaces. He cut the decals from a sheet that was a slightly lighter shade of grey than the surrounding painted areas.