Hmm unlock spell trick, I always tried keyring, didn't work that way. Thanks for the tip. *starts making boxes*
You can also use an armoire, which cannot be opened via Snooping skill. The only issue is you cannot open it either without putting it on the ground. Also, armoire seems to only weigh 1 stone, so make sure it has a total of over 10 stones to keep the whole thing from being stolen.
Tried it without unlock spell and locking, it still works for snooping protection. So good much awesome.