Hey,
We finally got the visa approved and we have been living for the last couple of months.
Not sure how it works in
Greece, only speaking for Croatia. And it's always different what is supposed to happen vs how you can manage to sort things out.
As LTShaw mentioned, for the purposes of applying for the visa, it's fine to use an Airbnb address. But once your visa is approved, you have about 10 days (don't remember exactly) to go to a Police station to register your address and request an ID. And here is where address gets more complicated as you are requested to present papers.
In our case, we presented a long term berth rental
contract on a marina, which ends in December 2024. They had to ask to a higher rank administrative whether this was acceptable or not, and after approved, we were asked to sign a handwritten letter stating that we commited to present a new address/
contract by the date our contract expired.
Not sure what happens if you don't go there 10 days after you receive that notification (email), but probably your granted visa get's revoked. Anyway, you would need to do so as you still don't have any proof of being legally. This might not be a problem if you get in and out of Schengen through Croatia, but for sure can be a problem if you do so through another country.
Also not sure what can happen if we don't present a new address by December (my bet is just nothing as it was super informal), but we've already made some friends willing to provide an address for us.
In case you don't have a marina contract, I'm not sure how you can solve it.
Also, talking to other sailors, apparently the acceptance of a marina as residence varies a lot among regions.
Hope this helps you!