The thumb for my Switch-button seems to get skewed(for on&off state). There were similar problems on github, but those were for people making libraries to support Switch
You can always horizontally stretch the graphic itself (ie, "switch_thumb.png") if you can't use the other answers.
If you use the original software used to design the graphic and re-export it after stretching, it shouldn't cause blurring of the image. You'll have to eye-ball it for your dimensions, but starting at +30% stretching should get you close.