400 lbs is laughable but lets go with it. At 8550 your pin weight is at least 1700 lbs (pin weight on a FW is at least 20%, and more often closer to 22%).
As far as your 400 lbs - Your not even close. The rolling weight Will not be less than 1000 lbs above dry weight, and more likely to be closer to 1,250 lbs. But you don't have to take my word for it, ask in a new post what is realistic. Better yet, search on this forum and see what others have reported their difference between dry weigh and loaded weight is.