I think the best alternative for you is to use a "tiled background" object instead of a "sprite" object.
It acts just like a sprite, but when you resize it, instead of stretching the image, it duplicates the original image, like a texture, or pattern.
You can't determine a collision polygon for a tiled background, but for a black and blue checkerboard, it'll do <img src="smileys/smiley1.gif" border="0" align="middle" />