FWIW,
- It might be worthwhile getting the "real world" weight of the RZR if you haven't already; maybe not the best comparison, but I was surprised at what my Ranger weighed compared to the book weight, even after factoring in the weight gain from the winch and full windshield.
- I have a 2009 2500 HD with Duramax. Back when it was my only vehicle, I routinely pulled with loads in excess of the manufacturer ratings (GVWR, GCWR infrequently) by a few to several hundred #'s, but within the tire and axle rating: don't like to do it, won't do it anymore (have other rigs now), but for relatively short tows (0 - 300 miles) it worked out fine.