Regardless of the gear ration {4:56 or 4:10}, Tow Haul still needs to be engaged unless you are running well under GVWR. I cannot understand why folks are reluctant to properly use their engine/drive trains. :h As noted the owners manual contains a wealth of information on the proper use of TH.
The engineers at Ford have been successfully designing and building these systems for a very long time. Another benefit of proper TH use is the engine braking on long down hills. Properly engaged you can descend long {as in 10 - 12 mile}, steep {6 - 8 percent}, grades without touching your brakes and you won't burn a drop of fuel.... what's not to love?
:C