Why not just bring the components of a seedsigner (raspberry pi zero 1.X, a TFT LCD+Joystick Hat, RPi Camera, and a micro SD card) as separate packaged components? Keep the SeedSigner ISO encrypted/obscured somewhere or download it from the internet once in hostile territory, if possible. Assemble components, flash SD card with SS OS, boot from card and recover mnemonic.
If you want to carry it assembled, you could even use a game emulation Linux distribution as cover, to make the pi zero look like a toy.


