What a funny read!!! The reactions and responses are so comical. I remember the younger years of exploring where these thoughts would cross my mind. I've been on cruises before and can't imagine a comfy or fun place to do this, but to each their own. Do whatever "floats your boat" if your sex life isn't fulfilling your needs.
As the administrator said, there are tons of cameras for legal and safety reasons, so keep that in mind. Weigh out your options, the risk vs. reward and go for it if you really need to! Night time on higher decks will have lesser risk. That would be my my best suggestion.