I agree with you about the binding fabric- on my screen, it looks too orange. Don't know if that's what it's like in person. I think either the mitten fabric for binding (you could do a red/blue to pick up both mitten colors) or maybe a green since you have some of that in the background. If you outline the individual motifs in the mittens you will lose some of the trapunto effect unless you do it before the quilting. Or you could do it by hand, being careful not to go through to the back and not to pull your stitches too tight. That way you could get a little definition within the mittens without losing the overall trapunto effect.
Rob