Well, you couldn't trust the device after they returned it. So losing it isn't a problem.
The best option is not carrying devices across borders. Have whatever you need online somewhere. Securely encrypted, of course. Buy a device at destination. And discard it before return. That's accepted best practice for security-conscious firms. They'll provide devices and online storage.
If you must carry a device in transit, it ought to be plain-vanilla, with nothing sensitive on it. Again, security-conscious firms supply such devices for staff. And private individuals can just say that they're too concerned about theft to carry their primary devices.
I'm thinking about a good device strategy. I think I need a disposable smartphone for situations like this. I should not lose any data if I lose the smartphone and nobody should gain any data if he finds/steals/takes it.
A lot of "freedom" fighters suggest this as SOP anyways. You keep all of your needed data in the cloud, and download on the other side of whatever security you are clearing. This goes for any device, not just phone. Some people even go ports on their laptops filled in with an epoxy or something so that ports can't be accessed. Of course, that just makes you look that much more suspicious. How paranoid are you, and what data do you really have that you don't want to be seen?
That's really irrelevant. The question should be, "what data does the government think I have, and what evidence do they have that I have it?"
Crossing the border feels like "guilty until proven innocent", which completely goes against everything this country was founded on. If I'm not traveling with my wife and kids, I'll put up a much bigger fight at security check points. Yes, it's annoying to the people who have to check me, but they're being paid for it (well, not while there's a shutdown) so I don't feel too bad.
If they do have evidence of wrong doing, it shouldn't be hard to get a warrant. We should be following due process at the border, especially for American citizens.
