You are not alone, I tend to take on water beyond simple condensation as well. I recently had the boat out 2 days in a slip and 5 days hard sailing. I don't think I took on any water in the slip (I installed an inspection port on one of the vertical surfaces) but had to pump throughout the trip, probably 5 gallons total.
We only have a few below-the-waterline and close-to-the-waterline areas to consider. Any submerged cracks in the plastic are likely not an issue as this is simply plastic skin over fiberglass for the hull.
Without weight onboard we only have the rudder bracket screws and the seam connecting the upper cap and hull in the rudder trunk. (why this was designed to be an underwater join is beyond me.) With weight onboard or while sailing, we also have the outside upper deck/hull join in the stern and, possibly on the leeward side. In the trip I mentioned above, choppy bays and weight in the boat kept the stern join underwater for long periods. I don't think it's the hull join in the centerboard trunk as I did not notice any leaking while in the slip. Same for leaks around the centerboard bracket hardware.
My plans over the winter are to inspect and reseal the areas mentioned. This will include removal/replacement of the rubrail and I have no expectations that the original will come off easily or intact. I have this crazy idea of dumping several inches of water in the hull and applying pressure to force water through the leaking areas but can picture the boat inflating like a balloon if I get impatient with the pressure!