Possible CCC Upgrade

So it looks like your new coach (the house part) is probably heavier than your old one. Things like the type of wood used in the cabinetry, the number of cabinets, the size of the slides, and a myriad of other things are eating up your carrying capacity. While there is nothing you can do about the ratings given by the chassis manufacturer you can certainly allow yourself some capacity by changing the springs, or adding a leaf or two. It won't change the rated capacity, however. You say the axles are the same rating, but make sure the wheels and tires are rated for the extra weight as well.