Just finished building a quick micro plugin for ClassicPress and WordPress, which allows you to add a verification link pointing back to your mastodon profile.
But not to just one, but to ALL your potential profiles (eg. I got two: one for my main stuff, and the other is for DJing + artsy fartsy).
Lazy being that I am, the settings are being displayed under Settings > Discussion => “Mastodon Profile URL(s)”. One profile URL per line.
Tested with ClassicPress 1.4. Released under the GNU GPL v2.
Get it yourself from the gist / source code. drop it in your plugin directory (preferable in its own sub-directory), activate, et voila!