[crote]

You're probably fine. Adapters do exist which make this a bit easier, but it's still going to be at least $100 in custom hardware. A curious thief is not going to bother with this and will just wipe the disk when they notice it's encrypted.

About difficulty: Given this article, I'd expect that most serious electronics hobbyists can currently do this. It's certainly not easy, but not that hard either. It wouldn't be too hard to turn this into a tool which can be used by anyone with a screwdriver, like what happened with the iPhone [0]. But again, why would a common thief bother to do this?

[0]: http://www.iphonehacks.com/2015/03/this-tiny-box-uses-brute-...