Just a late opinion.
I agree that with that GVWR - 1 ton would be minimal. If you're looking for a DD as well, consider an oil burner and at least 4.1- gears.
I have the 350 CC LWB Lariat - 6.0. I've been as much as 24k and the truck was as advertised. 9-13 mpg towing (pending conditions) and 15-19 emty (again, pending conditions)
Be prepared for proper maint. These oil burners are a little more expensive to maintain than their gas counterpart.
2007 FR 26DB Toy Hauler.
2005 F350 CC LWB Lariat - 6.0, 3.73. 5" MBRP Stainless Exaust. ARP Studs / EGR & Cooler Delete Terra-Grapplers.
2005 Ford Explorer XLT
1966 A-Code Mustang Coupe. Many Mods. (sold)
2006 Arctic Cat 650H1 - Many Mods.
2007 Suzuki Vinson 500. Many Mods.
Sampson: 1999-2009. R.I.P buddy. See you on the other side.
28 Nights in -'09.