Finally fund the source of the water in the boat. It was a hole in the speedometer line where the rear seat side compartments are. The speedometer line threads above the compartment, and is bundled to all the other lines going from front to back. I put my finger on the line while the boat was under way, and could feel a high pressure water stream. Another indication of a leaky speedometer line was a low MPH reading. After boating for the last five times, about one to two gallons of water drained from the transom plug. Now to fix it. But it was the best water leak I can think of. Could have been much worse.
Prior attempts to locate the source included backing the boat on the trailer into the water until the lake water was one or two inches from the top of the transom - no leaks on the inside of the transom. Also I silicone sealed the bottom of the rub rails, the bow cap, the bow eye, the bolts on the outboard, and two small stress cracks in the hull.