RE: shotgun or rifle behind the truck seat.
You also have to be careful about whether your state has a "preemption" law. Preemption in legal terms means that the state law trumps all county and municipal laws, such that no municipality can put into place an ordinance that is stricter than the state statute. In some places state law might say that a loaded but visible gun is legal, but without preemption a city could have an ordinance that says it's not and you could get arrested. Illinois is a good example. It is legal to possess a handgun in Illinois in your home, unless you live in Chicago and many of the surrounding 'burbs because they have city ordinances that prohibit all possession of handguns, anywhere. Illinois doesn't have preemption so these ordinances stand. Iowa, on the other hand, does have preemption, and possessing a handgun in the home is legal in Iowa, so it's legal in every place in Iowa and there isn't a damn thing a city council can do about it.
Mike