Clamp on Texture Import Settings

Hi, I'm trying to figure out how to get my shirt designs from Blender:

Into Unity. I've gone ahead and toyed with the Texture Import Settings dialog of the design image, setting the Wrap mode from "Repeat" to "Clamp". However, the results leaves streaking artifacts. I was able to turn off the Y-axis streaking artifacts by adding a second material, and turning the Alpha Clipping threshold up to 1 on the shirt design material... but I still have streaking on the X axis. How can I turn this off?