Will not work because your C drive with your OS will keep some of the information you think only exists on the thumb drive. You could>>>>
Take that blank laptop abroad. Upload anything you create into an Amazon, Microsoft or Google cloud service/
Before returning home you reformat your laptops hard drive thereby erasing all you did. Also you could mechanically destroy the hard drive and trash it before returning to America. So you return home with a laptop with no hard drive.
But if I were to go with your idea, I would carry it even farther.
I would buy a cheap laptop, send the info to a cloud or to my office machine and clean the drive as you describe.
Then after destroying the drive and leaving pieces in more than one obscure place, I would leave the computer for the house keeper in the hotel to steal.
Say I were traveling for Caterpillar on a multimillion dollar deal for mining equipment in SA, a $900 laptop would be an insignificant cost to keep China from finding out the details of my bid.
The real point of our discussion is that the bag guys that would commit a terrorist act against the US have already thought all of this out and will be way ahead of us and certainly ahead of the likes of “big sis”.