Most states have some form of "Castle Doctrine" whereas you may have a gun in your home for protection. Federal laws also allow you to transport weapons from one home to another if properly stored. Your trailer is considered your second home so federal laws say you may have a gun there. After all this it boils down to where you are and who is interpreting the law. You would have to be a real ass to an officer for him to bother to get a warrant to search your trailer(home) without cause. "I do not carry hand guns in my trailer but I do have a safe for valuables that I often forget the combination for." ;) Traveling out of the US is another story ... You must respect the laws of the countries you visit.