How heavy is that camper? That weight may put you into the severe duty oc schedule and if that is 3750 miles, synthetic would not be a good value.
Towing or hauling heavy loads is hard on truck engines. Does the engine have variable cam timing? If yes, go with a thicker 30 weight like Motorcraft Synthetic Blend 5w30. If not, 10w-40 will provide extra protection against metal-metal contact in the bearings because minimum ht/hs viscosity for 10w-40 is higher.