[Padgett]

Your selections are good with some exceptions.
1) The issue with TMs is usually not actual weight but the tongue weight. My 2720SL has a 460 lb tongue weight (measured). I suspect a 3124 is more.
2) Dodge Durango. To get the higher rating (2011-2013 is 5,000 lbs) you must have a 2014 or later with the eight speed transmission and the factory tow package.
3) Am biased but think the Grand Cherokee makes a better TV than the Durango because the wheelbase vs the axle to hitch distance is 3.27 vs 3.0. Under 3.0 is good. It is also lighter. Do you need the 3rd seat ?
4) While the Hemi makes more power it is also a less efficient & older design than the V-6. It requires midrange gas rather than regular and has 2 spark plugs for each cylinder that require frequent replacement.
5) For the RAM (or any pickup) get the shortest bed available with the crew cab.
6) If a truck I would suggest you look at the Ford F-150 with 3.5 (not 2.7) Ecoboost. That is the most modern system available.