By "backsplash area," I mean the area on the wall that is above the countertop and below the wall cabinets. At my house, it's 13". If I did that here, it wouldn't fully cover the bottom portion of this wall. In other words, the top of the wall cabinet would not align with the joint at type bottom of the triangular piece of drywall. I suppose this isn't terribly important. If I did a 13" tall backsplash area, there would be 5.25" of the bottom part of the wall exposed. Can I do an 18.25" tall backsplash?