Normally my big dog, Carlos, sleeps outside and the smaller terrier, Dwyn, sleeps in the front seat. That gives me the full back of the wagon for my bed, with both back seats pulled down.
On occasion a reason presents itself that merits Carlos sleeping in the car. The usual reasons are a) Carlos is driving me crazy barking (actually he does this much less now, having learned greater discretion in distinguishing between a threat and an interesting noise); b) it is raining and I’d rather have him in the car than getting muddy and wet; c) a threat presents itself, such as a bobcat cry, a neighborhood known for mountain lion activity, or an unidentified human.
In those cases, I leave up the narrower back seat and cover it with dog towels and other coverings. If I’m rested and feeling organized, I stretch a dog sheet or something else in a manner that creates a screen between me and the dog.
My sleeping space is thus reduced by close to 25% and its shape changes to an L-shape. Yes, I can sleep like that. No, it’s not as comfortable. I often do not get as good a night’s sleep.
Last night it poured. The dogs got wet. I toweled them off and situated them in the car. Today I’m tired. But the dogs are dry and safe.