Thanks, tinner. The gvwr of the tlr is ~19k pounds. That's why I used an excessive weight of 18.5k in my initial post. I've been doing this for 40 years and am very careful about loading, and always take it to a weigh station. The tlr will have the Mor-ryde individual wheel suspension with Kodiak disk brakes. Short of a total brake failure, stopping shouldn't be a problem.
And, I don't know how others are pulling these big rigs. Mine is set up to tow the max that Ford offers without being a dually. My 3.55 gears are all that's available with srw; 3.73's are for dually's. Yet, I see the big three, 350's and 3500 towing these huge 5's. They have to be way overloaded.