IMHO, there are two separate issues and they are not related.
The first issue is are you "legal" in the eyes of the state in which your vehicle is titled? You should be familiar with the DMV laws of the titling state and what "yardstick" your state law enforcement uses to determines GVWR. In my state, door post tags mean nothing. The only thing law enforcement "measures" is what your DMV registration reads compared to what you actually weigh. If you are over, you are illegal. Simple.
The second issue is what position the manufactures will take if there are part failures while you are operating the truck. By federal law, manufactures are responsible for the vehicle operating safely as long as it is operated under the manufacture's published GVWR. So, I want a "tri-square" relationship; the advertised GVWR matches the door tag GVWR which matches the registration GVWR.
So bottom line...determine what GVWR is used in your state of registration. Have your truck weighed on certified scales. Subtract empty from the official GVWR used by your state and thats the weight you have to play with legally.
Sure, aftermarket equipment may help your vehicle carry a heavier load better but such equipment is not recognized by any DMV and may "distance" your position with the manufacture if failures occur due to overweight operation.