They should be taking a average truck, off the production line if they are doing the weight themselves, or from a dealer's inventory like Consumer Reports does. Then check the weight. There, done.
I guess one problem is that Ford needs to have this weight information well before the production lines start producing the current and next model year trucks. So they do not have a production truck to weigh, for a few more weeks until production begins. So they must be using a hand manufactured truck, assembled the way the next model year truck 'should' be manufactured.
Fred.