Laguna:
Your friend has two somewhat conflicting requirements for his tires. For the off-roading your friend is doing, I would not recommend any 'highway' truck tires. Truck tires with HT or HL in their designations are primarily designed for on-road use only. These tires are designed to please todays 'soft-road' SUV owners who want their truck to ride like a car.
For true off-road use, (like Engineer and Black Bear Passes near Durango and Telluride), get a dedicated off-road tire. BFG All-Terrains or Goodyear's Wrangler MT/R would be good choices.
If money is no object, use two sets of mounted tires. For everyday use mount the highway tires. When you are going to hit the trail, swap on the off-road tires.
Trashing a highway truck tire on a trail is a costly issue, but getting stranded up on the trail would be worse.