But if the prosecutors can make a convincing argument that your intent was exactly that all along, then you may end up convicted anyway.

Intent matters. It might be hard to prove, but it matters.

It may not even be that hard; what other possible explanation is there for someone putting a PIN visible on their phone that wipes it while crossing a border?

> what other possible explanation is there for someone putting a PIN visible on their phone that wipes it while crossing a border?

Two obvious answers:

1. It's for the general case of lost/stolen phone.

2. It's for the owner. I can't remember numbers I don't type in, might as well keep it visible on the device.

>what other possible explanation is there for someone putting a PIN visible on their phone that wipes it while crossing a border?

For thieves, obviously.

There’s no way to prove intent if you keep your mouth shut and don’t answer anything.

claim your password to be some derivative of the duress PIN, for example: 1234 is password reminder for 2444 (one 2 three 4), the device is erased anyway.

For if someone steals the phone?

if the cops do that, they're breaking the law with that search already

theyll have a hard time showing that you intended for the government to break the law. first the government would have to admit breaking the law

They might be able to convict on that, but that sets a dangerous precedent imo, which is that doing anything preemptively to prevent searches is conviction worthy, including the preparation the OP suggested.

"it would be funny if the border police typed it in to my phone"

As a speech.