honestly i think if that is the case i would suggest looking for that obs crew cab, preferably with a 5.7l and a 5 speed since you don't seem to mind the gm's. it would be one step closer to your goal of a cummins in a crew. they tend to go fairly cheap as well.
i had a 95 gmc 1/2t that towed a 3000 lbs trailer loaded with a 5000 lbs truck and all my crap, over the appalachian. would have been a lot less scary in a one ton with decent brakes. the engine was almost redlined, but it did the job without complaint. albeit slowly.