I travelled for a week on Prince William brig of Thall Ship Youth Trust about 17 years ago around Ballearics and would say I cannot take sea sickness. Yes, narrow boat is stable because it is on rivers, but suspect it will shake in strong winds. A friend of mine lived on a narrow boat when she worked in London, but said it was nice, but hard work in damp and cold with lots of maintenance
Having said that, I am thinking I would prefer using Tesla Y model as land yacht. They have a nice DreamCase though I may find something cheaper. Since I have a family, I would use it to travel to client sites during the week - I worked as a consultant for a while, I am no longer strongly attracted me by cool hotel features, so lying down to sleep is all I need at the end of the day, David Lloyd will sort our my hygiene problems, if it is not around - well, then there are toilet tissues
And I used to live in Budapest as a student for a year - our dormitory had only a microwave, so, if I previously managed to live for a year using a microwave and a fridge, I can get through 2-3 nights using a camping gas stove, warm up army rations in a kettle or buy an alternator and operate a microwave to warm up ready meals from M&S