Good heads up on the payload. I definitely need to do some math.
I went back in my notes and it appears the last time I weighed the camper (loaded with gear, no liquids in tanks) it was 4300 pounds. I grossly misremembered that.
I have wanted a 3/4 ton truck for a long time but the rational part of me is having a hard time justifying the additional costs and the reduced fuel economy. 90% of the miles I will put on a vehicle are unloaded highway miles.
Fun part of me would love a Power Wagon or F-250 Tremor. More realistic part of me translates that to 1500 Trail Boss.
This is the best and worst part about choosing a new rig - it's dialing in which compromises you can live with most easily!
Something to consider based on my use case:
I drive a GMC Canyon, a midsize truck with a 3.6 Litre V6. It's always running just a few hundred pounds below my max payload as it's always got the drawers, fridge, cap, tent, etc. installed and we tend to like the "just grab your toothbrush and hit the trails" freedom. But, it means that it's always driving around within spitting distance of it's 6,000 lbs GVM, whereas normally GM Canyons would be running around weighing about 4500-5000lbs. That extra 1000-1500 lbs of stuff to move means the little V6 - which is a great little motor - has to work a good bit harder in my truck than it would in an identical truck that was configured differently. I see a big hit on my mileage - especially when towing.
Meanwhile, for a time I also had a fullsized truck that was also 6,000 lbs, but it had a 4.8 L V8 motor. So, where the V6 had to rev like crazy when going up hills, drinking a lot of fuel when doing so, the bigger truck barely saw the RPM spike up more than a few hundred for those stretches, and in the end despite it being a bigger motor and a much less aerodynamic shape, the big truck got fuel economy that was comparable to or better than the little truck, based on how I use it.
As you said this is worth doing the math on - you may find that the slightly higher fuel consumption in the bigger truck is actually a bit of a wash when compared to the potentially significantly higher fuel consumption of the 1500 series truck that would need to be working extra hard when loaded up.
2500 Diesel looks to be around 19 MPG, the 1500 Diesel looks to be around 22-26 mpg. Some quick napkin math here:
At 19 MPG, assuming an annual average of 20,000 miles, you would be using about 1,052 Gallons of fuel in the Big Truck.
At 22 MPG, assuming same annual average of 20k miles, you would be using about 909 Gallons of fuel in the 1500-series truck.
At 26 MPG, same assumptions as above, you would be using about 769 gallons of fuel in the 1500 series truck.
Average gallon of gas in America right now is $3.14 per gallon.
This means that your fuel savings per year by going to the 1500 instead of the 2500 will range from about $461.00 if you have a thirsty 1500, to about $889.00 if you are light on the skinny pedal. It's not a lot when weighted against the potential benefits of towing/hauling your adventure equipment more safely and easily. And, when towing, the economy of the 1500 series takes a major dive - down to about 13 MPG. If you are only towing a few hundred miles a year this is likely a moot point, but if you are towing regularly or driving heavy regularly, the hit on mileage to the 1500 series might make the 2500 series more appealing.
