A far bigger concern to me would be to make sure the truck can handle the weight. 15,000 pounds will have a pin weight of at least 3000 pounds plus the hitch at around 250 pounds. And on top of that, of course, is the weight of all the people, dogs, tools, and all the rest of the stuff in the truck. A one ton truck such as your are considering will be a good choice.
This is precisely why I am intent on buying a 1 ton. 15k was the very upper limits of what I looked at. I would say the average gvwr of all the floorplans I looked at were around 13,500 with a dry hitch weight around 2100. The GMC has a payload capacity of 4250ish and I figure with a hitch that will leave me with 4k lbs. Most of the time it will be only my wife and I, but I also did the math for 4 passengers and should be ok. The extra payload capacity is the primary reason for going 1 ton.
At the Ford dealer yesterday, the sales manager, who also happened to be a towing expert kept trying to convince me I'd be fine in a 3/4 ton, despite my rationale for needing the extra payload for the hitch weight.
We plan to camp a lot with a week or two vacation each year, so we don't need a huge 5th wheel to live in. We're both in our mid 30's and fully engrossed in our careers, so I don't anticipate needing to upgrade to anything larger or more luxurious any time in the next 10 years. Because of this, I think we'll be just fine in a lighter 30-35 fiver. In fact it's entirely possible a fiver is too much, but I do want to be able to vacation the national parks and scenic parts of America in comfort.
Anyone with a similar life style and needs decide they needed more 5th wheel after RVing for a bit?