My little guy is either a 6-12 months or 12-18 months in the waist and hips but needs a 2T in the length. I have lengthened the Sandbox pants in the past but they just had the solid front piece and solid back piece. With the front of the leg being made of 3 panels, do I still just pick a center point and add all the length there? I don't want the panels to look out of proportion. Do I need to redraw all 3 pieces combining the correct width and lengths to make a custom pattern? Thanks for any advice!