We had a 2011 Pinnacle and pulled it with a 2500HD Duramax SRW, our first trip from Florida to TX was a white knuckle trip.
The wind pushed us around quite bad, moved up to a 3500HD Duramax DRW and went coast to coast last spring, ride and stability was great.
Upgrade to heaver truck was well worth the money IMHO.
We fulltimed in or Pinnacle and it had a Pin Weight of 3,700 lbs and total weight of 15,700 lbs.
Does not take much stuff to get the weight up there, also we had Dual Pane windows and a Washer / Dryer which added quite a bit of weight.
We loved our Pinnacle, it served us well, great 5th Wheel.
Robert & Bale the "Traveling Dog"
2012 GMC 3500HD DRW