I have the Sherling scales also. Boy what a surprise when I weighed in at 1,440 tongue. I had added two additional batteries to the two that were already there to feed my inverter, plus about 20 gallons FW. Since they are all full forward, it added almost 400 lbs to the tongue weight. The published tongue weight is 1,040 lbs.
My unit was figured from the factory [according to the manual] with two 30 lb propane tanks and one battery, but empty FW tank which is FAR forward. Sure wish I could put all the batteries in the back end.
2013 Silverado 2500 HD Duramax/Allison Tuned
Aviator Wright Flyer #1919
"First In, Last Out". 11B4Y
DAV, MOPH, VFW, 5/7 Cav,1/8 Cav Assoc.
11th ABN Pathfinder Co. N7MIP