When you want to work a stranded swatch, you really don't have to use the colors of the pattern. Even if you use only two colors, you can work the right side on a dpn, switching colors as you go in a ratio similar to the pattern, then slide the work over to the right tip, stranding both yarns loosely across the back and work the right side again. And again.
Or you can do like me and measure your gauge after you get started, increasing one needle size from regular stockinette.
I've started a sweater, and the first inch showed that the gauge was too tight, so I switched needles at that point. Nobody knows.