No, although most gauchos come with brackets to attach your mattress to the wall or ceiling it doesn’t mean you can use it as a truck bed.
The reason for this is that if something were to happen while driving, like hitting a bump, then your mattress will fall backwards which means you have no protection over the back of your head. Or if something were to fly up from the road and hit the gaucho bed, there’s nothing there to stop it from coming through your mattress too.