Yes, you are correct that a Tradesman has a higher weight rating (payload and trailer weight) than a Power Wagon. However just to clarify the original post is asking about a Tradesman WITH the Power Wagon option package which effectively reduces the weight ratings to the same level as a Power Wagon. The only reason I am posting this is to make sure somebody doesn't think you can do a Tradesman with the PW package and somehow skirt the lower payload and trailer towing capacity associated with the Power Wagon. It is the lower rated tires, taller and softer suspension, etc... that comes with either a Power Wagon or the Power Wagon option package on the Tradesman that reduces the capacities.
These next comments are not specific to the post quoted above. If you really need higher payload and towing capacities and the off-road capabilities of the PW you can always modify the truck with aftermarket parts. Obviously you lose the factory warranty on those parts and the ability to role the expenses up in monthly payments, but if you need it then you need it. The first option is to start with a Power Wagon and modify the suspension and tires....though the payload will police will jump on here and comment that "legally" it doesn't change the rated numbers on the door sticker, which is true. The other option is to buy a Tradesman, or even one with a Cummins in which there is no PW package available, and modify the drivetrain with front and rear lockers, aftermarket suspension, etc... Just have to review your needs and punch some numbers to see which makes more sense cost wise. Considering the PW option package is $8k you would have some money to play with in regards to modifying a truck.
Making a statement that one can buy a truck with the PW package and then upgrade the vehicle to increase the payload really, at best, begs the question of why someone would buy a power wagon package only to remove just about everything (but the winch and some graphics) that makes it a power wagon. At worst, someone thinks all they have to do is put new shocks on it and, voila, it has tons of capacity. The sum of its parts designs it for a purpose not commensurate with heaving towing.
It isn't just about the numbers printed on the door, it is heading off into the unknown with more mass than originally intended and then moment arrives where an unexpected event occurs because some part, either original or non-specified replacement part fails due to the mismatched combination. The hope is that this event only impacts the driver, but sometimes it ends up impacting others and all arises from a "hey y'all, watch this" moment where someone knows they put the right parts on and the numbers are just made up.
And using the truck not as designed voids the whole warranty and any extended warranty, plus adds potential liability problems elsewhere. Losing warranty on the aftermarket parts pales in comparison. Read Ram's warranty policy, specifically why it will void a warranty.
If one wants to tow large, one buys the right truck and tows their fun-vee to the trail.