In my opinion you'd be much better with a laptop that booted to windows and looked like it had some simple things installed under a password you don't mind giving them. Then they'll probably never get around to asking you about the usb stick your tailsOS is installed on.
You can now get extremely large usb sticks in very small form factors. I have been toying with the idea of creating something that looks exactly (and nonsuspiciously) like a usb 'charging cable' but with built in memory. Ideally if it's plugged into power or a laptop, it just appears as a normal usb cable, but if the microusb end is not plugged in, it shows as a large memory stick you could also boot from.