Update: I ended up purchasing the Cooper Discoverer H/T plus tires as they were on sale for a price that I couldn't pass up. Just a little over $400 for the tires (275/55/20) plus $56 to mount and balance. If money was no object, I would have bought the Michelins LTX MS2's. I just could'nt justify it now.
I picked up my brand new Bullet travel trailer last week 200 miles across the state. I made sure I air up to 50 LBS in the rear and 45 in the front. The set up was nice at 60-65 mph. Always felt like the truck was in control. In fact, the ride is a little harsher than I thought it would be from XL tires. I can't imagine what 8 ply tires would feel like trailering my ultralight.
As my Denali is a 90% dedicated TV, yearly mileage will be limited and I'm sure I'll be replacing tires for aging vs wear years down the road. Thanks for everyone's input.