By the way, here are the numbers for my 2011 Ford F350 4x4 SRW, 6.2L gasser as per the CAT scale:
Steer Axle 4220 lb
Drive Axle 3000 lb
Gross Weight 7220 lb Truck was empty with a full tank of gas and me on the scale.
GVWR is 10,800 lbs
One other note, I will rarely need to fill the water tanks to capacity. I don't need 2 batteries as I will have a built in gen, and a solar panel, and my truck engine will charge the battery. I also pack light, so doubt I will need 500 lbs worth of stuff. So, I really believe if the above estimate is pretty close, I will actually be closer to 4,000 lbs than 4,500.