A style similar to the sailor’s, because it uses the lines, is the geometric one, or plaid or rhombs. If there are many lines, the color space is smaller and thus the visibility of the problem area is reduced. Attention to the colors used, if they are too light (pale or pale pink), it is a bit more exposed, but a dark navy blue, dark green, should not create a problem.
For a casual outfit, a shirt and jeans shirt is an ideal combination. We can use here, for example, a blouse / dress divided in the area, bounded by these lines, in the sub-arm to be a safe color, and in the rest area any color you like. Because I try to reduce as much as I can the insecure zone, I will use some geometric figures (the triangles are best in my mind as well as some irregular ones) and thus I get an interesting and colorful outfit. Some pictures as an example: