Middle school can be challenging in the best of circumstances. When you live in a sticker-covered van with a crystal-collecting, sage-burning, free-spirited mother and an unconventional, sometimes moody father, it’s virtually impossible. “Unsinkable Cayenne” is a historical novel in free verse. By turns poignant and humorous, this voice-driven Junior Library Guild Gold Standard Selection will be a new favorite for fans of books such as “Alone” and “Starfish.”