>If you are going to double-wrap, it'd be best to wrap the payload in your custom package first and then standard second on the outside, so someone has to overcome the first barrier before they can find anything out about the custom/second barrier.

Quite a typo here. Replying to clarify as edit timeout has already expired. I meant you should use the standard wrapper on the outside layer so it appears to be ordinary until someone breaks down that first layer.