Printing solid yellow background, or Bold/point size +/- first ,then printing a negative of C&O in black, +/- a point size etc, on that might mask over the yellow for a crisper edge & look.
Registration with a reverse like this, if off register, the white would blend visually into the yellow and would be less noticeable than other colors would.
Same kinda light trick as the blue vs gold dress illusion. Effectiveness is in the edges here.
The opacity of black you use may be better or may be purple and show near yellow.
Another thing about white is the white edge when trimmed, no matter what color is printed on the top, if it contrasts, the white pops.
