Pulling a 2012 Flagstaff TT that has sticker wt of 7800 lbs with cargo of 1300 and I am getting close to that. Changed my WDH out to a Blue Ox 2 years ago which made a BIG diff especially in sway issues, hear similar comments with other folks that have upgraded their WDH. I pull with a Chevy 2500 with extra cooling on trany, temp never runs above 180 in worst high temp days in some pretty good hills. No issues on engine pulling hard, run around 1600 - 1700 rpm at 67 on the Duramax. As others mentioned something going on there. Tip I got from vendor at rally, use a laser heat measuring gun at axles to check bearing temp to see if all are similar.
Marriot2 on Wheels 2017 Flagstaff Classic 832 OKBS
2013 GMC Denali 6.6L 2500 HD DMAX w\Alison Trans
Pepper Pomeranian rescue 101 days as camping buddy
Days camped in FR, 2011 = 20, 2012 = 57, 2013 = 59
... 2014 = 39, 2015 = 52, 2016 = 68, 3 more planned