I had a 2014 Ram 2500 with the 6.4L Hemi and 4.10s. I towed a 12,000# loaded 5er with it. The RV was 37' long and had 3 slides (2010 Cougar 322QBS).
The Hemi hauled it around without an issue, even in the mountains. I never felt it lacked for power, ever. High RPM when climbing grades and 7-9 mpg when towing was the norm. On flat ground with no wind, it was either 5th gear at ~2200 RPM, or 4th gear at ~2800 RPM. If you're ok with those things, it'd be a good choice.
I had 2 Cummins powered Rams before the Hemi, both were modified for more power. I had no regrets.