The Container should be your best option regards, safety, It has 2 opening doors at the rear with a locking bar on each door, If you use a good Lock, they only way you can open them is with a Bolt Cutter, the containers are a sealed Vented Metal Box with ply board floors at times, also incorporated in the floor / sides strapping point, I used to carry the 20fts + the 40fts. use the net to purchase, depending where you are the unit / container trailer will del, but ring around Enfable.