Have the duress password also activate the various sensors on the device and start shipping data to the internet. TSA agent's face, everything that's said, etc.
How so? Presumably there would be nothing in the UI to indicate that it's recording anything, and the data would be stored outside of the restricted container.
Have the "duress password" bring up a container with plausible faked call, text, browser, camera, etc, history.
Oh, and allow for user defined number of container/password pairs, for when the TSA asks for both passwords.