If you really feel the need, you can add additional administrators to Tuskfish. Just bear in mind that they will have exactly the same powers that you do. What could possibly go wrong?

• Download a copy of Tuskfish and run the installation script on a local install, entering the details (email, password) for your new admin user.
• Open the database for your site in DB Browser for SQLite, view the user table and make a copy of the row for the Admin, including their password hash.
• Download your production database and add a row in the user table containing the new Admin's details.
• Upload your production database back to your site and reset the permissions for the database file to 0600 (read/write by the owner, only).

That's it. Your new admin should now be able to login with their email address and password.

If you are using two-factor (Yubikey) authentication, you can also enter their Yubikey ID (first 12 characters of the key's output) in the yubikeyId field of the user table and they will be able to use that key to login (there are two Yubikey fields, so you can have a main and backup key for each user). Each admin needs to have their own Yubikeys, they cannot share them as the key ID is used to identify the relevant user record.