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.
I think you are correct about the lethal drug reaction during a rape, but to properly dispose of a body you need three things: a place, a plan and time. I do not think Deepak and Satish were around when she died. I think Joran was by himself at the Fisherman's Huts. My guess is he ran about 3 clicks to his house and told his dad what happened in full panic. After some conjecture, his dad helped him move the body back to the Sloot house. This move gives them the time to develop a plan and place for the body. Joran uses Steve Croes boat to dump the body the next evening within 2 miles west of Arashi beach... the currents and winds will move the body out to sea. When the Holloway family and friends showed late that night, the PvdS tried to create the Casino alibi not knowing how the plan ahd panned out. Joran returned to the house as Pvds lead the family on a tense goose chase.