well this is the 40' one, and he got the 40+5 which adds 5' to the garage so but for the 40'er
Model FTL4005
Axle Weight 9610 lb.
Hitch Weight 2990 lb
GVWR 17000 lb.
Payload 4400 lb. (the rest must be water and gas?)
but still even the hitch weight thats quit a load, like you say at least you have a dually, Id look at getting the extra j endorsement or whatever depending on where you are from...