I have met people from England who spend their winters in Florida. They do transatlantic cruises in each direction--no more expensive than flying if you choose an inside cabin, and you get 2 weeks of pampering in each direction. And no limits on how much luggage you bring.
I have never met or read about someone who used cargo ships for the same journey--I will definitely read your travel blog! Maybe I can do that myself when I'm able to retire. Thanks for sharing!