A joiner tour to Caramoan is a big no-no given the length of land travel. Lucky for you, you still made it to the island in 15 hours; worst come worst, it will take less than 20. 20 hours in a cramped vehicle! The most common causes of delays are peak-season traffic and blocked roads. Tourism will boost there if they construct express ways; if I'm not mistaken, they have already started building.