If you are a guide, I would be looking at a gas powered Super Duty 07 and up. Likely crew cab what ever bed you want 4x4.
I have a Tundra and it is a good truck but it has some short comings. The single biggest is it does not have a limited slip. I know Toyota claims there is one but there is NOT. It has a traction control device that applies the brakes to the slipping wheel in hopes that the other wheel will gain traction. What this does is wear on your brakes and causes unnecessary torsional rotation on your axle shaft that is have the brakes applied.
Having used my truck in the mud and snow, it is at best marginal. A factory Ford (or any American company) LSD works much better. I would guess that this truck will spend a bunch of time in the dirt and that is something to consider.
I said a 07+ Ford because of the solid axle and coil spring suspension Ford uses. The 05 and 06 gas motors with 3 valves could be... finicky. They went to a new 6.2l in 08 with the then new body style, an 07 or 08 might be fairly inexpensive. The suspension is really good off road, the cab is big to keep clients comfortable.
