Why? Why not just put any data you are worried about on a very small storage medium? Hide that and smuggle it through. Concealing a small SD card must be a lot easier than buggering about with elaborate, and there for suspicious, schemes. Let the TSA do what they like with the laptop.
Oh, and whats this assumption about running a safe PC from home? You have read the Snowden stuff, right? And even if you cant go with all that, if you are at the US border, while your PC is in , er, Berlin, who says that as you stand there spooks are at your house raiding all the data they like? You know, if you are of that much interest to the authorities. And if you are not, SD card type thing.
Lastly, if one is all doom and gloom (maybe a bit foil hat) about this stuff, like me, I'd assume the buggers had the data I was worried about anyway, if I at some point it had been on an electronic device with communications capabilities.