That is GM's OFFICIAL position from a warranty position too! LEGAL from a LEO/CVEO is a totally different standard. Legal from a civil court, is also a different standard.
From my use of sadi truck, assuming I still had 4 teenage adult sized kids, that 5w would put me overweight in more ways than one. Then again, my family of 6 came in weighing in the 1300 lbs relm as noted when they were teens. Add in 1300 to 1600 and you are close to 3000 lbs of net payload needed. It is probably there, but reality is, one will be bottoming out the rear axel with this much weight in the truck in many conditions. as such, from experience, I will not recommend one have this much wt in a GM 2500 series crew cab truck with a 6000 lb or there about RA. A single wheel with the 6400 lb rating might work......but reality is, you will want something in the 7000 lb plus ra capacity to do what I would do all the time.
Like ALL things great and small, you mileage and what you can or can not do with a given rig, is up to you to figure out.
Marty