Something I keep forgetting about here, is the OP's truck is a cab and chassis. His door sticker is NOT on the truck. He has full rights to modify the setup to work for him IF he likes current truck. IE, he CAN put higher capacity tires and rims, He CAN put higher capacity springs to hand more load. also make sure the brakes are up to the task. Then all he has to do is up his paid for gvw to match what he weighs. His door sticker will never be checked, nor verified as he does not have one.
One of the joys of getting cab and chassis trucks. They CAN be modified from the way the chassis manufacture made them.
On the other hand, I can see how a 45/55 series truck might be a better all around option here too!
Marty