I'd bet the OLM is pretty close. Driving around in low range defintely takes it's toll (not to mention the frequent start/stops). I was able to keep the iron in the single digits on a 1-2K run in my 2.5L using Delo SAE30. I thought that was pretty good given it's a 95% trail rig. Gary recommended tracking gallons of fuel burned, but I've been lazy.
Anyway, I'd run the Torquepower 10W30 for the summer and then run the 5W30 for winter. Switch back to 5W20 when your stash is gone. I'm actually planning a trip to Moab in early Oct and am thinking about which oil to run (3 months before the trip, and I'm thinking about oil...LOL). I was going to either keep the Delo SAE30 in there, or do my winter change a little early to either QS green or Valv white in the 5W30 flavor. I also have a qt or two of QS torquepower 5W30 sitting around (may make a blend). Looks like the average temps range from 35-45 @ night to 65-80 @ day. That would be fine for even the SAE30 (pour point of -24*F).
Forget the Hemi. I'd finally break down and buy a JK if they came with the 2.8L diesel. I suppose you can buy one from AEV, but if I'm going to spend $50K, I'd buy a Ford King Ranch Crew Cab Doooly first.