Let the guessing begin. “The Power Trip,” the 29th book from Jackie Collins, features five jet-setting couples on a Russian billionaire’s yacht who bear remarkable similarities to real celebs. “I had so much fun writing this book, I can’t even tell you,” Collins told The Post’s Richard Johnson. Page Six readers shouldn’t have any trouble guessing George Clooney inspired the “50-something movie star who never wants to get married and who was voted ‘Sexiest Man Alive.’ ” There’s also “a gorgeous Spanish singing star who decides to come out of the closet” — calling Ricky Martin — and “an English superstar footballer with a designer wife,” but he’s African American, so of course, it’s not David Beckham. And the billionaire’s girlfriend, a dark-skinned supermodel, can’t be Naomi Campbell. “My supermodel has two legs, and she’s not on crutches,” Collins laughed. The toughest guess in “Power Trip,” out Tuesday from St. Martin’s, is “the cheating politician who goes after every intern,” she said, “an interesting character to write because you can put so many names to him.” The couples are put to the test when the yacht is boarded by Somali pirates. Collins said, “There are so many serious books. I like people to have fun. I call it a sexy, sun-drenched thriller.” Clooney, we’re sure, is thrilled.