Sorry to bring up such an old thread
One thing EVERYONE seemed to overlook is how the "weight" rating of a pickup is done... IIRC, to get the ratings, they have the weight within 13" of the front of the bed... the weight of the load is right behind the cab!! Not spread out over the entire floor of the truck... albeit a slide in does place weight towards the front of the truck because of the overhang... it still adds some weight clear at the back too.
I agree with the later statements about the COG issue... I think it is simply a "safety" thing to prevent someone from flopping their rig over onto it's side... but I have one and just this weekend drove by a corvette that was upside down... hmmmm... maybe we shouldn't worry about the truck as much as we should worry about the driver???
I think you hit one the head... most of the newer campers are just too heavy for even 3500s (going by paper), but they carry them just fine...
Steved