Nothing is ever enough, Anymore ,The bad guys find there way around everything
CaperJ is correct. If someone wants your info bad enough and they know a few things, there is little you can do besides disconnect your connection every time you aren't actively using it.
As a rule of thumb, I do not store personal information on my main HD's. Instead I have a external HD that I turn on when I need to work or store personal things and turn it off when finished. It may be a little crazy but nothing is overboard nowadays.
not sure about the kangaroo idea, seems good in older days but the problem though is that you have to shut down the computer, plug it then restart. Seems better to me to get a extranel HD and use the very flexible USB