It's been a seriously annoying thing at least as far back as Morrowind. If unowned containers aren't going to respawn or dump items, why don't they tell us that? Every long term Bethesda fan has a horrible box ate my stuff story, and one of the top questions every time a new ES/FO comes out is where can I stash my stuff without it vanishing.
Right across from the saloon in Goodsprings is a house where Easy Pete sleeps. You'll find two beds in there, one of which has a footlocker at the end. The footlocker is safe, as I've been using it for over 130 hours. I sleep in the bed, and keep my gear in the foot locker. No problems.
Enjoy.