I know that in y state (Georgia) I can purchase a $150 annual permit and tow anywhere in the state on that (I think up to 12' beam) and No flags or escort. FL is pretty good about this as well, not sure the fee, but it would be 2 tows, one in , one out and a week a part is what I am thinking. So a seven day permit once year is all that I would need.
Nobail - your Dodge 3500 would have the same drive train as the 2500 with the difference being a stiffer suspension and the rear end gear. The F-Series Superduties are the same idea, same drive train (Engine/Transmission) and only a difference with the suspension and the rear gear.
I will admit, that many times the tuning is different, but that I am not concerned with as I have a tuner and have have a custom tune written to account for the load and the gearing with consideration for the tire size.
I am also familiar with Load Distribution so can do that if needed. Overall, how would you rate the power production and ease of putting that load with your Cummings? This may be the final deciding factor for me on a Marlin...