In other posts I have related some experiences I've had towing our Cougar High Country 319RLS with our 2012 Ram 1500. Due to overload concerns I upgraded to a 2014 Ram 2500. Both were/are gas engines. There are literally hundreds of questions when trying to figure out what kind of TV to pair with a given RV that I thought sharing what I've learned might be of some help to a prospective RV buyer.
The RV: 2014 Cougar High Country 319RLS. Listed weight: 8025lbs. Actual loaded weight: 9042 lbs. (grey/black tanks dry, 1/3 fresh water).
2012 Ram 1500 4x4 Quad Cab: 3:92 axle. 5.7L Hemi. Truck weight: 5300 lbs.
GCVW: 15, 500 lbs. Tow: 10,050 lbs. Payload: 1406 lbs.
2014 Ram 2500 4x4 Crew Cab: 3.73 axle. 6.4L hemi. Truck weight: 6500 lbs (from memory?). GCVW: 19,500 lbs. Tow:12, 500 lbs. Payload: 3171 lbs.
The obvious problem with the 1500 was payload. I was right at the limits on everything else and loaded the RV lightly due to that. We also carried very little in the truck. I added Air Lift 1000 air bags to help with sway.
My observations: The 2500 is a much bigger truck. It has a crew cab vs quad cab on the 1500 and it is considerably taller and more difficult to maneuver. The ride is terrible vs the 1/2 ton. This is primarily due to Ram requiring 80 psi in the rear tires and 65 psi in the front - unloaded. You can air them down, which helps a lot, if you don't mind the little low tire beacon staying on. In 2014 Ram apparently "upgraded" their electronics in the trucks. I've not seen any positive benefits but it did make it so the rear view camera will not show up on the big screen in the dash. It is in the corner of the rearview mirror which is about useless. On the highway the truck is very quiet, solid and soaks up the miles as did the 1500.
Comparing the two you give up comfort (ride quality) and nimbleness with the 2500. The 5.7L in the 1500 seemed more responsive than the 6.4L in the 2500. That is not to say the 2500 is a slouch and it may just be some electronic tuning of some sort. The 6.4 is a stronger engine, and feels it, it just doesn't feel like it responds "quick".
Towing is the reason I bought the 2500. The 1500 pulled the trailer OK. It was susceptible to sway even with the Equalizer 12k hitch and air bags. Not white knuckle stuff but enough to make you tense on a windy day or busy freeway. The kind of stuff that makes you exhausted at the end of the driving day. The weight issues never left my mind. I worried about anything and everything. We were just about maxed out in virtually all categories and I'm sure over our payload. Now I have plenty of margin.
In other posts there are lots of superlatives used to describe bigger trucks, diesels etc. for towing vs a half ton - night and day; no comparison etc. In this instance I couldn't say night and day (that would probably have to be a 1 ton diesel) but there truly is no comparison. To me for everyday use a half ton is the way to go. For a larger trailer the difference a 3/4 ton truck makes in towing is very noticeable and welcome. Make no mistake; the suspension on the 3/4 ton is far stouter than the 1500. It literally stabilizes the trailer for towing much more than the 1500 could. The 6.4L feels so much stronger towing than the 5.7L did although the numbers wouldn't indicate that. I can actually use cruise control and not worry about it and the engine is typically spinning about 2200 - 2400 rpm. Gas mileage is also better than the 5.7L. I was averaging about 7.5 - 8mpg with the 5.7L and over 9mpg with the 6.4L.
I didn't really want to make the TV change but felt I had to for the sake of safety. I knew I didn't like the ride of a bigger truck, and still don't, but if you're going to tow a heavier load you just need to do it. I'm glad I made the change; it improved the towing experience dramatically and now I'm back to trying to keep myself awake while driving instead of being tense and worrying all the time