The solution is simple. Continue calling the boat Boaty McBoatface. Ignore all references to the government's preferred name. They can choose what's painted on the side, but the name depends only on what people call it. If enough people call it Boaty McBoatface its name really is Boaty McBoatface. If your job depends on calling it the government's preferred name then subtly alter the timing of your speech to make it clear that it's not the real name while maintaining plausible deniability. Only written communication from coerced people remains a problem, and hopefully that will be far outweighed by people using the real name.