If you'd like to be horrified, Alpha Phoenix shows how to make election maps that don't look like they've been gerrymandered, and might be hard to spot what is wrong with them!
It might be a trope by now, but when you mention "rich tourists and digital nomads"... have you read For The Win?
When Cory Doctorow considers this question, ... His character, an archetype of the subcultures you mention, voiced by the most cyberpunk author you ever read, chooses a cargo ship.
Looks like the main options are the things you've already ruled-out:
Lowest impact travel: passenger on a cargo ship.
Zero-emissions vehicle: £6000 trip on a sailing boat, but any normal-sized boat is going to expect everyone on board to take shifts.
Maybe you can find a "tall ship" that's big enough to have passive passengers (example), or pay the small boat to bring a higher ratio of paid crew to let the passengers sleep.