As a matter of fact, that's what I was doing to bypass DynDNS limitations: running a PhantomJS script via cron once every week to login, click around and logout. But it is a tiny hassle anyway. Much better to stick around with a service that does not have these annoyances.

And that's just what I did with https://github.com/kopf/dyndns-autologin . A few months later, they discontinued the free service altogether.

Somewhat sadly, it was my github project that seemed at times to garner the most interest from outside, even though it was just a shoddy python script thrown together in a 10 minute cigarette break at work.