The main thing about towing is the weight ratio between vehicle and trailer. As the PW is as heavy as the other 2500's, the only reason for having a lower towing weight is tongue weight. The more tongue weight you have, the more stability the rig has when driving. That is obviously limited on the PW (at least without air bags) as it will sag more and the bottoming-out reserve of the suspension is less. On top of that the springs are softer, so the truck is more likely to bounce when going over road imperfections. So my purely amateur guess is you're probably good towing more if you keep the tongue weight in check and don't go below 100lbs or so. Especially if you have an anti-sway coupler.
It's similar for hauling, you can beef up the springs with air bags, but the shocks are still softer, leading to an increased risk of bouncing as the spring/dampening ratio is now changed.