There's one way to look at it, and that's that he'll be just like 1/2 the other people you see walking around a CG. Over weight. Doesn't make it right. Just is what it is.
To the OP, if you're financially buried in your truck and have now way out of the TT before delivery. I would suggest getting a tire upgrade at the minimum. Install some air bags to help with handling or maybe Timbrens. And look for a used Hensley Arrow WDH.
None of these will make your truck into a 3/4 ton but if you have no way out, then working on the trucks carrying capacity is the least you can do. Pack light and drive carefully. At the very least make it work for a couple years till you can upgrade trucks.
As a side question, did you sign any papers obligating you to buy the TT upon delivery? Even loosing the deposit would be better than doing unnecessary upgrades on the truck.
If there's anyway possible to back out of the TT, then do it. Look for something lighter. The floor plan you're looking at is a dime a dozen in TT's. Try looking in another town. We got out current 5'er 300 miles away.