One thing I've found useful for traveling with a large dog (75-pound Golden) is a car hammock. It protects the back seat (bench seat) while providing the dog with more security than sitting on a seat. It also keeps shedding fur contained rather than getting into the seat fabric. Cost is usually between $25 and $35. Just search for "Dog Hammock for car" on the internet (I purchased mine from Amazon). It also came with a safety strap which attaches to the dog's harness.