My buddy is planning to tow his 4,000lb boat (wet weight, all in) up the Coquihala and to the Okanagan on his 2016 Toyota Highlander v6. The car has a towing package and is rated for 5,000lb. He’ll be travelling with his kids in the car so I warned him of the hot summer days and the horror stories of towing up the Coq in hot and long summer days and suggested he might be better off with renting a truck just for towing the boat and get his wife and kids to travel in the suv. Not sure if this was just too conservative but is a highlander really capable of safely getting them up the Coq and down to the valley with that size of load in the tow?