Replicating a paint scheme

I would mask, personally. Paint the light color first. While this is drying, find a design which matches the one you want (or make one) and print it out. Place wax paper over the design and secure both of these to a mat or flat area with pins. Cover it with a light colored, flexible tape like Tamiya Masking tape, and use a curved blade to trace the outline. Pull away the inside, and cut a rectangle around the cut, use this to mask the plane, and paint the inside color.

From your description of it, I would paint it.  The real trick is how complex  a shape the "swoosh" is and whether or not your hand is steady enought to cut it out.  For something like that, I would first spray the fuselage where the "swoosh" appears in the color of the "swoosh".  Then cut out a "swoosh" mask from Tamiya Yellow tape.  For cutting, you can lay it down on a self-healing matt that you can buy in an arts & crafts store or the drafting section of an office supply store.  If cutting long curves free-hand proves difficult, you can cut very narrow strips that you can bend around to form the shape, and then use mour tape to fill in the field of the shape.

After applying the "swoosh" mask, burnish the edges of the tape ans paint the rest of the plane.  Try to go as light as possible around the perimeter of the mask and try not to really point the airbrush into the edge.  What you want to avoid is piling up a lot of paint on the edge of the mask.