The 273MK is almost exactly the same as my Fox except for length as far as weights go. I towed it for 6 seasons with a 12 Ram 2500 Cummins. My 5er was 9300 lbs loaded and the truck was 9800 lbs for GVWR. My pin was 1800 lbs. Not to sound ignorant or redundant but most of the time I never noticed it back there. I'd opt for the Ram Cummins in a heart beat.
I have since switched to an 18 Ram 6.4 4.10 gears. There's a big difference in towing mpg and tow ability.
I would've like to bought another diesel but my driving habits are not conducive to a diesel.
With the miles you plan on racking up a diesel makes perfect sense.