You need to weight the truck to see what your real payload is. Based on the dry weights you provided the pin weight on the 5th wheel will be in the 2200 to 2800 range. You will likely be at your GVWR and just under the Tire rating on the rear axle. Only way to know for sure is to weight your truck full of fuel loaded up like you were going to take a trip, add the 5th wheel hitch weight to the rear axle number, and do the math to see what your real payload is against your posted weight sticker.
I had the truck in my sig before I bought a 5th wheel, Weighed it with friends 5th wheel hitch in bed, when I was looking at 5th wheels I had the real numbers to work with when looking at trailers that would work with it. Based on the ones I looked at an 11,000 dry weight will put pin weights in the range I described above.