IMO, that is exactly what has happened!!!!
And if the girl had a bad reaction and died from the pill, especially if she'd just been raped, the young men would absolutely freak. She couldn't be left on the beach, because people had seen Joran and the Kalpoe brothers with her. And if she'd been raped, they'd know that would show up in an autopsy, so the body has to disappear. The boat scenario sounds plausible because it's hard to bury a body at short notice. You have to get a shovel or two, dig for maybe hours, and then what if cadaver dogs find her? All that effort for nothing. Besides, Joran strikes me as someone who prefers to delegate the dirty work to underlings, and the Kalpoe brothers and DJ definitely fit into that category.