You may want to hook-up your RV to your ‘Cat and drive to the nearest truck stop. Most (Loves Pilot etc.) have certified scales on site. You could pull through the scales until only the trailer tires remain on the scale. I would then add say 15 – 20% for tongue weight and you should have a very good idea as to total weight. Published boat and trailer weights do not account for batteries, gas, tackle, etc.