Once again I think it is good to remind people that any job that you take, or business you run, when in a foreign port is probably illegal without the proper work and/or business visas.
Yes, a lot of people do this sort of thing, and very few get caught. Here in the U.S. we call them "illegal aliens." It happens everywhere. If you want to do it, I won't judge. I only wish to remind you that there are risks.
Oh yeah, and if you get caught... I don't want to hear any whining!
Interestingly enough, there is a primary relationship between the sort of person(s) who would live onboard a (sail)boat, and the basic human freedom which would allow people to earn a living and co-exist anywhere, peacefully.
For those of us who have eschewed the landlubber anchor / rut in our lives, we would also be most comfortable with expecting the right and the freedom to go where we want and do what we want as long as nobody else is hurt by our actions.
Sailboats are emerging as the best path to that diminishing freedom. We are that which can slip through the cracks, globally, of the controlling "authorities", much to their dislike.
We can cast off our lines for anywhere in the world without having to be scanned, stripped, searched, licensed, certified, taxed, checked against any lists, we can carry whatever quantity of liquids we want, we can say words which would easily earn a free trip to Guantanemo, (without any actual "crime" being committed), wear what we do or don't want to, and generally thumb our noses at the uniforms.
"They" don't like this, but for now, they can't do a damn thing about it.