Dodge had some frame problems when that body style came out. On the chassis cab duallies it was common to have problems even when under the legal loads the truck was rated for. A search can turn stuff up, but I have figured that the easiest fix is to cruise to a local welding shop able to do good work. Sometimes you have to find a shop able to repair actual truck and car frames, out here most weld shops are qualified even if they don't do mostly car and truck repairs.
I figure out what super duper hitch I want, sounds like you have yours. I make sure everything is out of the way so they can bolt it on, you already did. Then I let them bolt it on, weld it to the frame. And then we play a game of how much more metal we can add.
I bought a boxy body style chevy used and it had a bumper/hitch setup but some of the brackets were pulled loose when the bumper was hit. The guys fixed all the stuff that was there then added more braces and stiffeners and in many cases I get them to weld the frame up so it is thicker as well, just welding plates onto the frame basically.
I used to work in a spring shop and the other guys in the shop could stretch and repair frames on class 8 trucks and on down. Overall their opinion of new stuff sucked and whenever someone bought a new truck they brought it in to do the super duper job I described above.
You can easily add 50 pounds of metal to the back of the frame, but I find it easy to add tow hooks and what not and any problems are readily apparent since there are plenty of braces that give way before the major ones close to the hitch do.
I like the idea of a new truck, but the old trucks had extra metal from their poor technology and overall I like the old ways better since these problems seemed less common unless you overloaded the truck.