So according to your own figures you will be 100 pounds over GVWR when you put the 5th wheel pin on your hitch. When the trailer is dry. So what ever you add to the fifth wheel will add more weight to your pin weight. Also the hitch itself may add 150 pounds. I myself would be interested in what your rear axle weight is loaded. I would scale that and add about 2000 pounds plus the weight of your hitch. See what that weight is. You may need to upgrade your tires. I say this because I have a 9500 pd dry 12000 wet 5th wheel that I pulled with a 2008 3/4 ton Chevy duramax. My pin weight was right at 2000 pounds. I was definitely over when I pulled this rig but it appeared to me to be fine. I do believe there is no way you will end up under your GVWR. But that's up to you, I certainly did it and felt safe. Now I drive a 1 ton 2011 Chevy Duramax and there is a big difference. I will say now I feel safer. I am sure your engine will do fine you just won't go as fast up the big hills.
JMHO
