Nice truck. I did the same thing, I quickly got tired of my 1500 constantly changing gears, revving to high hell to maintain speed and getting about 7mpg towing my trailer across the pass. I sold it and got my 2500, it doesn't even flinch when going up the pass, all while getting about 12mpg.
Hemis are essentially balanced and blue printed engines from the factory like we used to do years ago. Better though . Running at higher rpm doesn't bother them at all, and they're better for it. They run cleaner when they run at higher rpm.
But in all honesty people aren't buying half ton trucks to pull, they're buying trucks to replace cars. There's a distinct payoff. My dad always told me, "You can buy a truck to get great gas mileage or you can buy one meant to pull, but you really can't get both." After a number of engine/gearing/model combos I have to agree. If your 1500 was behaving like that it wasn't properly set up to pull.
That's why the ram HD trucks are so great, they actually do have some moderate success doing both. Now, since I have several duallys for my business I'll never use anything else for towing. But I do miss the luxurious ride of the 2500.
Truck below is one of our 15s, 4.10 gears, that's a custom cyclone we delivered to an end user and tipped the scales at 19,830lbs. Recorded 13.8mpg average over roughly 1,400 miles.