Hank, Ours is the 4R110. I've driven a rental Class C with 5R115, as well as an F350 with Bigfoot Truck Camper on it. My impression is that the 5R isn't superior because of one more gear choice on its menu. Even without using Tow/Haul, it simply makes better shifting choices. Ours drops out of OD at the slightest provocation, especially on cruise control. The 5R is more likely to use throttle when it needs more power, instead of immediately shifting like the 4R.
There may be another reason - our chassis is 2002. Later models apparently have a different engine control module and with that no doubt different strategies programmed in.
But back to your original question - If you have a V10 with 5R110 and of course aren't running overloaded - I would not anticipate toad towing problems.