My wife and I will be taking a Royal Caribbean cruise (Haiti, Puerto Rico, St Maarten, St Kitts) at the beginning of April. She has fatigue and mobility issues and I'm concerned about being totally out of contact if she wants to lay down while I go elsewhere on the ship. Not concerned about off-ship excursions as we'd be together. I'm considering walkie-talkies, but would be easiest if we could just use our phones to Text/SMS. Not worried about calls, just need to know if she needs me back in the room. I've seen that VZW has Cruise Pricing, but how does this work? Also, would we have to purchase the RC Zoom Data plan?
I'm not sure about the options you mentioned, but you may want to check with the cruise line to see if they have communication devices available.
When we did a Disney cruise, they had two (limited, but serviceable) cell phones in our cabin that we could take with us anywhere on the ship and talk to anyone else in our party once we knew their "number". They only worked on board, but with a dozen of us scattered on different decks, it did help us keep in touch.
RC may have something similar, included or for an extra charge. Normally, using the ship's wifi is costly, as is cellular outside the US.