F250 CC SB 4x4 6.2-3.73 or 4.30 for 10,700lb travel trailer

I need to ask, is this your first diesel? That and have you towed with a manual before?
With gas most people slip the clutch a bit when starting off, that isn’t necessary with a diesel, you can pretty much, as soon as the truck starts moving let it out and go!
I tow a 32’ 5er at about 11,500# with a 5 speed manual with 3.55 gears. In traffic I use 1st a lot in traffic towing or not, much easier on the clutch.