I've towed for 3 years or so up and down the east side of the US including mountains almost every other month. I just came back from a trip in northern Georgia two weeks ago. I just ordered a 23 Sierra 3.0 because I have to keep my truck empty due to lack of capacity. While it totally rocks from a towing perspective the fact that I can't use the bed for pretty much anything is what's making me up size. The Sierra will give me another 400 lbs of capacity and that's all I will ever need for just the two of us.
As others have stated a half ton trucks capacity is one of the biggest issues when towing an RV. Once you factor in your tongue weight and passengers it doesn't leave much for any cargo. My trailer is a 25 foot box, 30' including the tongue. The dry weight of the trailer 5300 lbs for me and does not include the two propane tanks and most trailers mount the battery on the tongue as well and it's not included in the dry weight either. I wouldn't tow without a weight distribution hitch W/ Sway control. The problem is most of the hitches are in the 75 to 100 lb area so this needs to be factored in as well on the trucks capacity. I use an Anderson WDH hitch because it was the lightest and it's quiet compared to the spring bar models when turning. Just be mindful of the label on your drivers door of your total capacity because it creeps up quickly.
Also, things like where on the trailer is your storage, forward or aft of the trailer axles? Are you going to be "boon docking" if so where on the trailer are the all of the holding tanks forward or aft of the axles? Between Fresh water, gray water and the black water tank they can change your tongue weight considerably thereby reducing you truck carrying capacity.
Keeping your tongue weight at around 11% to 12% (min of 10%) of your trailers weight will really keep sway down to a minimum (still using a WDH W/ sway control). I recommend getting a hitch scale it's worth the $ for piece of mind. It really helps when loading so you can balance your load to keep all the weight in the desired zone. I typically travel dry except a few gallons in the fresh and a few in the black tank, this is in case of a unplanned restroom need.
This is my current set up until the new ride comes in existence, 2018 Colorado long bed with a 2.8 diesel.
