newbie start from zero, nothing, nada !

The 2500 is going to be the safer choice what do think about my numbers here ?

Two thoughts. First most folks look to bigger trailers or RV's so if you get a bigger truck you can go bigger with the RV without the need for another truck.

My second thought is that at least on the Ford towing site (you mentioned Ford in your response) the normally aspired gas engine loses 2 percent of power for each 1000 feet elevation. GM gas engines are probably exactly the same at altitude reductions. At 5000 feet like the Denver are you will be down 10 percent of your tow rating just for altitude. Also Ford specifies that the frontal area also has a deduct for fifth wheels and travel trailers. Add both deducts together and the tow rating drops to perhaps where you are number wise or even less. Go bigger and have the margin, brakes, etc. that have been mentioned by others. As a previous poster noted a travel trailer is not a boat and perhaps towing a boat is easier for both tongue weight and frontal area. But, you are towing a travel trailer. As to the daily driver part of your decision process, I have had two 2500 (three quarter ton trucks and one 3500) and they all are just fine. I really don't see the big daily driver difference between a half ton and a three quarter ton as they are the same size for parking, etc. What is different is payload ratings.

If I was purchasing a new gas truck to tow a trailer today I would look hard at the new Ram 6.4 gas engine. It appears to be designed and built for working and preliminary reports are coming in at around 16 mpg empty on the highway and 10 or so towing trailers about your trailer's weight. And it has plenty of power for that bigger trailer of fifth wheel you will want in a couple years. I think the 6.4 with a 4.10 axle will tow 16,000 pounds. Just a few years ago only the diesels could tow that and stay within the tow ratings provided by the manufacturer. But, whatever you get the most important thing is to use it and enjoy it.