I have obedience trained dogs for almost fifty years, so it goes without saying that I'm a dog lover. I bought my Class A coach eleven years ago because we had aging pups that we didn't want to leave behind any longer when we went on vacation. We currently have three: a nine-year-old rough Collie, a two-year-old smooth Collie, and an Aussie that's seven. We have tried various restraints for our dogs and found none that work because these dogs are too intelligent and will figure out how to get out of them. My Aussie knows if she presses the red button, the seat belt will unhook and retract. When we pick one of them up when they're puppies, we bring a crate with us and set it up on the floor, secured to our dining room table so it won't slide. But other than that, we don't restrain our dogs, and I have few worries about them being involved in an accident. There are two reasons for that viewpoint.
First, the dogs are in positions where they won't hurt my wife and me if there is a crash. The smoothie travels in my wife's footwell. The Aussie lies on the doghouse, and the large rough Collie stays on the recliners located in the slide-out behind the driver's seat, so he can either sleep or look out the window. None of the dogs are where they can fly forward and hit one of us.
The second, and most important, reason is because I was an OTR driver who knows how to avoid accidents. If this is your first time driving an RV, consider this: when you drive your dog in your car, do you drive the same way as you do when the dog is not with you, or do you slow down, take starts, stops, and turns very slowly to avoid making the dog carsick? If the latter, this is the same way you need to drive your RV. A Class C is going to feel more like a car or van than a Class A, and you may have the tendency to drive it like a car. Please don't do it. Take your time every time you are behind the wheel, and never rush to get anywhere. Take your starts slow. Give yourself extra room behind the next vehicle so you have plenty of time to slow down or stop when necessary. Don't keep your eyes on the vehicle in front of you. Instead, look as far up the road as you can see, hopefully a quarter mile, so you can anticipate potential issues that will force you to slow down or stop. This will give you more time to react, and besides keeping you out of accidents, your dog will love you for it. This is the way I drive my RV with three dogs, and they have never had even a close call in the past eleven years.