Regarding tongue weight measurement.....Instead of getting fancy and carried away, just go to your local fishing store and get a fish weigh scale. They are inexpensive, small, and pretty accurate. I tossed mine in the trailer and took it with me on the road. Took two seconds to get tongue weight when hooking the trailer up. BTW; I found my RT622 was happiest with tongue between 18 and 25 lbs. regardless of total load....