First off, kudos for being proactive about managing your anxiety while planning for a cruise. I know the thread is a bit dated, but hey, better late than never, right?
You're right, the busy nature of a cruise might naturally keep your anxiety at bay. But it's always good to have a game plan. The first thing I'd suggest is contacting the cruise line about their policies on CBD. Some are more flexible than others, and it's better to know upfront.
Also, have you considered having a back-up support system in place? Depression hotlines and mental health hotlines often offer services for anxiety as well. They are staffed 24/7 and can offer immediate support.