The back of an SUV is really spacious for a big dog, and now you can protect them from the painful bumps that make him or her bang off the hard plastic floor. Available now from Big Barker: https://bigbarker.com/products/suv-bed
If you have big dogs, you are probably quite keen to find a cheaper sleeping solution that those offered by pet stores. You can pick up a bed frame and crib mattress at most any Salvation Army store and build this dog bed yourself, probably for half the cost of a pet store bed. Bonus points if you use a bed frame you already have!