Take a pencil. Draw a line on each side of that knot starting at the widest spot, right on the edge (should be at a right angle to the center of the knot) and follow the grain carefully, going both directions, both edges. That is what your profile should be. Measure between the lines and see what you have. 15 inches from the tip puts it very near mid limb. You will be under 1 inch wide, handle side of the knot. Understand that with any width taper, there will be necessarily, some violation of the grain that is perfectly acceptable and unavoidable. The angle of that violation is the key. Around a knot like this, the angle will increase sharply at spots, and that can be a problem if your not careful. Draw the lines and see what the degree of violations will be. Touch up the lines if you need and see what you end up with. Needs to stay a little stiff (flat) at that knot in my opinion anyway, so you might be ok with it.