I did exactly the same thing going from an 08 silverado 1500 to a 2010 2500Hd for pretty much the same reasons. Our new 14 White Hawk took us close to or over the tow limits of the 1/2 ton. We have a diesel [duramax / allison] and love it.
You will probably notice that the WH tongue is higher [at level] than your old TT. In our case it was significant and the highest adjustment on our Reese hitch receiver/bar was still too low. Ordered a taller bar [$150 on line] that gave me the extra height. Take it to a tire store or auto shop and let them swap out or adjust the receiver. It will take a heavy duty impact tool to make the adjustment. The dealer tried to jack the tongue by going up on the chain links and that got me home, but was not the solution. A bar with more adjustment holes in the riser fixed the problem.