Preheat the oven to 350ºF. Spray a loaf pan with non-stick spray. Set aside.
In a medium size bowl, whisk together the flour, baking soda, salt, and baking powder. Set aside.
In a large bowl with a handheld mixer, or the bowl of a stand mixer fitted with the paddle attachment, beat both of the sugars and butter on medium-high speed until light and fluffy, about 2-3 minutes. Add the eggs and beat again until completely incorporated. Add the banana and the water and beat again until everything is combined.
Reduce the mixer speed to low and slowly add the dry ingredients, stopping when everything is just incorporated.
Slowly drizzle the caramel sauce into the batter then stir a couple times to swirl the caramel around. There is no need to make sure it's fully incorporated.
Pour the batter into the prepared pan. Bake the loaf for 50-60 minutes, or until a toothpick inserted in the center comes out mostly clean. Allow loaf to cool in the pan on a wire cooling rack before serving. Drizzle with more bourbon caramel sauce, if desired, before serving. Loaf stays fresh, covered tightly at room temperature, up to 5 days, or in the refrigerator up to 1 week. Loaf freezes well. Remove from pan and wrap tightly in plastic wrap and foil, and freeze up to 2 months. Thaw in the refrigerator or at room temperature.