Here's my 31' Dutchmen behind my '12 Hemi. Loaded on the scales weight between 7400 and 7800lbs depending on tank levels. Dry weight is 6,873lbs.
This put the rear axle right at limits of 3875lbs out of 3900 and front axle at 3175.
I have airlift 1000 bags in the coils int eh back set at 35lbs and a Blue Ox Sway Pro hitch with 1,200lb bars. Tongue weight is between 900 and 1,000lbs which makes payload the limiting factor. Any less than 12% tongue wight and the sway was brutal. Also the porpoising on these trucks is usually caused by not enough weight transferred to the front axle due to an improper WD hitch set-up.
Scale ticket
Steer - 3175
Drive - 3875 (note this is over GVW of 6,800lbs by 250lbs, but under axle weights by 750lbs and under tire weights by almost 800lbs per tire with load range D tires)
trailer - 7550
GCW - 14600
View attachment 57519