You can get a low mileage (around 50-75k) used 2011+ F350 6.2 4x4 w/ rear locker for under 20k.
This is what I would go with for that trip.
They need spark plugs and wires at 100k and not much else.
The CCLB gets a 48 gallon tank so no need for jerry cans.
I have a 96 7.3 diesel and love...