Just because you are barely within specs of the truck does not mean that all is fine & dandy.
The first time you hit an exit ramp turn too fast you are going to wish you had alot more truck. When you get caught out on the open on a windy day you are going to wish that you had alot more truck. When you are going up & especially going down those very long western mountain grades you are going to wish that you had alot more truck.
With a 2500 you will be borderline but you will have lots of company out there. It might be OK if you are doing short weekend hauls to the local CG but if you plan on doing some real long haul traveling there is nothing like have more than enough truck for peace of mind & security when things are not perfect.