Even if this works for now, for you, you have only solved the problem for yourself. But the problem of privacy is a collective problem in society, so unless most people have privacy, you don’t have it, either.

This would be like commenting on censorship/non-free speech laws that you’d solve it for yourself by using Tor or some other anonymizing method. That would not solve the problem of a society which will lack free speech, and if a society did not have free speech, you would have problems, even if you’d manage to somehow get free speech for yourself.

I've been doing this while going between the US and China. Once you get used to it, it is only a few minutes of hassle to restore everything. If it is so suspicious, they should have no problem articulating that to a judge and getting it from my email provider or my storage provider. But I suspect they only do it because they can and if you add even a tiny bit of friction, they won't bother unless there are other things that make them suspicious.

They'll just consider that suspicious and confiscate the devices ¯\_(ツ)_/¯

Docker for phones. Encrypt and upload image to server. Wipe. Cross border. Download and decrypt. Image.

It could probably be implemented as a one-click service on some devices.