P-metric is fine. The empty truck doesn’t have much weight there, and even a good sized travel trailer or boat is only putting tongue weight over the rear tires. I might air my p-metrics up to 40-42 if towing heavy. Tires were never an issue… shocks and weight distributing hitch were much more central.
My boss has those milestar ATs on his truck and admittedly they have been a workhorse tire. Remind me a bit of cooper ATs. Of the list, those would be my first choice. Surprisingly quiet for what they are. Good, heavy tires. I would also consider the Firestone A/T as well for good value.