It is not too difficult to print your own on an inkjet printer. For that small a plane, you can do standard page size sheets. Spray a piece of paper with Photo adhesive cement - very light coat from a distance. Let it dry a bit and press your silkspan down onto it. Use a low ink setting or the color will run all over the place. When you are done, brush the back of the backing sheet with paint thinner, kerosene, lighter fluid, etc to get the glue to release.