Those are some really good tips, thanks everyone!
I do want to improve my skill so that I can feel comfortable cutting 1/4" and thinner stock without a backer, but now that I know it's a common practice to use one, I'm okay with it. I'm going to practice with thin scrap to build my confidence. But for now, I'll stick with the backer for the pieces I'm going to sell or give away.
I never considered that the blade size might be part of my problem. I've used Flying Dutchman UR blades in the past and like them, so I'll order the #1 size to see if it helps.