Yes, hot caramel can be dangerous, and if you are not comfortable flipping it, let the tart cool until it's barely warm. Shake the pan to see the pastry is still loose. If not, place it on the stovetop and gently heat it just enough so the apples are loose. Then, flip the warm tart. This method should not have hot caramel. Once inverted, if you want you can reheat the pastry in the oven as well.