Turning Lucas Strong (The Guardian Series, #1)

I'm doing a series (ebook only) of novellas, 27 in all. The first and last are intro and finale books, the middle 25 are 5 novella sets for each of 5 main characters, so they can have the same cover and just swap out the subtitle on it--5 models total. I'm unsure if the intro and finale cover should have all 5 models or if there's a better way to portray a group of alpha males who engage in a competition to determine the ultimate alpha among them. But I want to keep everything as close to a single template as possible for ease of shopping on Amazon and uniformity of look.