Your dog should only be allowed in the back of the pickup in a crate that is securely tied down. If you do transport your dog in a crate in the back of the pickup make sure there is protection from overheating or chilling. Never leave the dog in the crate in the sun. Provide water often on warm days. Dog seat belts are available to secure your dog from jumping around in the car.
Crates can also be strapped down with seat belts and used to keep the dog secured.
A crate may be helpful if your dog gets car sick. Keep water available for your dog as you travel. Overheating can happen quickly causing heat prostration and death. Special travel bowls are available with no spill lids. Also freezing water in the bowl provides cool water as it melts.