If the leak occurs with the jack down, it is a result of the body / chassis flexiing and a gap likely opening somewhere and allowing the water in. Problem with leaks is water can can enter in one place but it shows up in areas further away.
I know you are in Florida but I would consider trying to get an appointment at the Thor Factory Service Center in Wakarusa, IN. They have a rain booth that will find just about any leak and allow them to track it down and fix it properly. They shoot water from the bottom, top and sides and it is like being in a Tropical Storm.
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