We just moved from a Windjammer 3065 towed with a 2010 Tundra to a Grand Designs Solitude 369RL pulled by a 2013 Ram 3500 Laramie Longhorn, Cummins with Aisin and 3.42 gears. We did our Maiden Voyage this last week from ABQ to Loveland, CO. The truck pulled amazingly well, and the trailer pulled great with no issues. We weighed in at around 24K with 5 people in the truck, full tanks, 2 dogs, and an extra tailgate. I have a B&W Companion Slider with the factory 5th wheel hitch. So far, there is nothing I would change, which for me is a pretty big statement.
Here is a pic:
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