That’s an interesting question…spy stuff…cool!
Obviously, strong passwords are required on the device (not on sticky notes in the wallet ;-)
Okay, the fact that you have an iPad makes this more difficult because opening up an iPad multiple times (before the trip, after the trip etc.) is not trivial and exposes you to potential accidental damage that is quite expensive to repair.
You could, once the device is open, simply disconnect the antenna’s from the logic board. While the WiFi would still somewhat work, the range would be really poor and any snooping would have to be done within immediate proximity.
A more hard core approach would be to remove the power going to the WLAN IC but it’s unclear if this wold cause other issues as a lot of these IC’s talk to each other during the boot process. What’s odd here is that I usually repair devices, not disable them so I can’t say for certain if this would work.
The golden rule applies here in that if you give the black-hatters direct access to your device, they will find a way to get in or correct anything you may have done to harden your device. You have to take an onion-like approach, multiple layers of protection against remote snooping and direct access.
If this is a real concern and not just some mild paranoia, you should look into getting truly hardened devices for this purpose.
Let’s get the other moderators in on this, they may have some interesting insight!
@mayer @oldturkey03 @danj @jayeff @arbaman