Lol, as long as the Carolina girls go for it, its all good.
But as example, the 4wd suburban has a gvwr of 7500 lbs and weighs around 5800 lbs. So you have available payload of 1700lbs.
The 2016 3500 Suburban, which is fleet only, is made of beefier components. Things you mentioned like axles, transmissions, cast iron engine block etc. It weighs more, 6585lbs, but has a gvwr of 11,000lbs. So payload on that is 4400lbs. That's more than my 2500 Silverado. That's heavy duty! Probably rides like a tank.
I don't know if the 3500 Suburban would still have the buffering issue this thread is dedicated to. I suspect the sheetmetal is the same as on the 1500 version...