Tumbless uses two passwords: the admin one could benefit from the local storage approach, however I'm not sure if chrome's password saving feature would help. The second one is the one you share with your guests if you choose to make the blog private. I see no other option here.

I'm not very happy either with the hidden file approach, as it might be vulnerable to brute force attack. Amazon does not specify what kind of protection they have in place. I definitely recommend hard to guess passwords.