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.
