Unless your blue hexies are each 4" wide, you're good. If they are wide, you could outline each of them through the center.
The rule about the 8" is the width between stitch lines, not the length of your stitch lines. Some people will even stitch only vertical quilting lines with nothing horizontal at all & it turns out beautifully. Your plan looks really nice. Hope you post a pic when it's all quilted.
