Don't get your tailfeathers so twisted. You originally asked about a truck with a 16' bed (see your first post) and I asked for pictures. So here come the pictures but without explanation so one would naturally assume it is the truck in question. OK?
Now..as for not needing a hoist I was making fun of the fact that with an 84" CA (7') that would be less than half the length of the 16' body you referenced. Hence it would nearly tip on it's own.
Chassi ratings are determined by many many factors chief among these are axles, wheels, springs, tires, and frames. Then come engines and transmissions and a ton of other things. The sum total rating for the least rated components is the GVWR which is a combined FAWR and RAWR.
As for getting the wheat off one can always shovel it or nearly all elevators have truck lifts.
