The “normal” leading edge construction uses a 2” strip of material folded in half. On plans like the Escape, the sail material goes all the way into the fold, so the rod is following the inside edge of the material. The leading edge does not make the wing larger than shown by the plan.
Maybe you are using the term “fiberglass rod” generically, but in case you aren’t... the spars called for in the plans are tubular carbon fiber. That makes them very light and stiff. If you substitute a basic, solid fiberglass rod, the kite will require a lot more wind to fly, and it’s it’s characteristics will be very, very different. (Probably not for the better, but hey, who knows?)