If you really don't care about unauthorized access, just write the password in sharpie on the box. I have a bunch of machines hooked up to test equipment that sit on their own network. I just write the username and password on the box and no one ever needs to worry about trying to find the sticky note or find me and ask or waste time guessing. The name of the computer, the username, and password are all the same and reflect what the box setup for.
I also endorse writing the "password when passwords don't matter" on the side of the machine. ISPs have been doing it with their gateway modems for years, and I've never heard of any threat model that calls that out as a problem.
