The first and second hides are probably your best bet. The last two are a bit too open.

Honestly, the biggest problem with big tanks is not security issues, but temp and humidity issues. It is VERY hard to keep constant and correct temps in such a large tank. Humidity is also a nightmare since you will most likely be stuck using lamps to keep the heat up. The lamps will in turn lower your humidity.

My best suggestion to you is to either use a tub until you can get a more appropriately sized enclosure, or just buy a different tank/reptile enclosure. It will make your life a million times easier. And your snake will be happier