Your method will work, but it's going to be a little tedious. I would paint the sunburst without any numbers. Then lay out the numbers as one stencil. Then tape and mask the stencil to paint the two colors one at a time using the previously painted sunburst as your guide. In other words, lay the stencil down. Tape and mask the red portion and paint the white. Then tape and mask the white and paint the red. Then remove the entire stencil. Be sure you let the wing cure completely before putting the stencil down. Don't want to pull up the sunburst with the stencil. I use a heat gun on low setting to loosen the glue on the stencil and pull very slowly.

Paul