I think the easiest way to get around this would be with a mobile hotspot /travel router.
Connect travel router to ship wifi, and do princess login so that internet data is available at the router.
Set up your travel router to host a hotspot, sharing the internet connection.
When you set up the travel router, require a password to connect.
Whatever your final device is ...
laptop, tablet, another phone.
...those devices think they are connected to secure wifi, which requires a password.
(because the travel router is presenting secure wifi, requiring a password).