One thing that I think helps to determine GCWR are your brakes on the truck. Should you have an RV brake failure your truck brakes will only stop just so much weight, in your case guessing #23,500. Of course no one looks at that, its always, oh mine pulls it just fine, just keep in mind all that weight has to be stoppable too. Plus, just because the RV weighs #15500 when hooked to your truck you also have to know if that is the GVWR of your RV, after all you will be loading it with personal belongings and camp supplies which add up to more than what you might think.