In MD it is a felony to leave a firearm accessible to anyone under the age of 16. I don't believe hanging on a door covered by a towel no matter the height would qualify as compliance. In answer to the question of how a child could gain access to something you thought was safe my 3 year old grand daughter moved a kitchen chair and climbed up on the kitchen counter to get peanut butter to make a sandwich. Lucky thing P.B.&J isn't a weapon. Not seven feet off the floor but illustrates their ability to do things you didn't think they were capable of. Maybe you wouldn't know that if you don't have children.