the GVWR is only a assumed weight load..  if you surpass this load your
vehicle will not "fall apart or blow up"..  i have loaded over 1500lbs of car parts
(engines, body parts, seats, etc) into a 84 vanagon (with car tires on it!)
and the trip went just fine..

its just like the "suggested serving" on a box of potato chips.   :<)

chris