Simulating number boards on long hood end of Athearn GE motors.

What is the best way to simulate number boards on the long hood end of Athearn GE motors (“U-boats”)? I tried cutting holes in the shell, but it was tedious work, and the result was a far too deep recess. I’ve looked at a lot of prototype number boards in service over the years, and it seems that they are almost, if not for the gasket, on the same plain as the surrounding metal. Any ideas? That is , short of giving up and buying Atlas?
Thanks.

Why not just add decals with the engine number in the appropriate place. Incidentally, if you model Santa Fe, many of the long hoods on their units did not have number boards.