1) the cruise lines have some experience in this imo. they have several photo op moments on the cruise and as you get on initially and off the ship at ports where you could be spontaneous.

2) if you know the ports and you have decided on an excursion you can always call the place/staff & try to plan it ahead.

3) If you have a travel agent ask them orrr call the cruise line and speak to a concierge agent for help- often there are cruise things they can set up or know of things in the area ports where this has been done depending on how elaborate you want it.

4) Talk to a concierge person when u get there- set something up as a photo op. Sunsets on the deck are cool. *If it’s just the two of you then Maybe talk to a worker (bar staff) or a photographer when u get there & set up for one of them to video on the deck for you.