I had an idea: package PAM (like what you did with PortableApps Backup) with an encryptation tool, or something that protects the "Documents" folder with a password. Sorry for my English, I'm a Portuguese student. It's also my 1st time in the forums.
Welcome to PortableApps.com. I don't know how to word this and not sound mad (i'm not mad) but use the search bar before posting a question.
I did so and found this: https://portableapps.com/node/11729
It should answer your problem