With the tire changes you made, it is a judgement call.
IMO, with a good load in the truck (350 lbs of people, 500 lbs in the bed) I would run 40 psi in the front and 50 psi in the rear tires on the highway trips. It doesn't need that much, and 35 psi would be OK, but that is my recommendation. With only driver and no cargo, 35 psi should be fine.