This is such a unique question, I don't think anyone has ever been in that situation. My advice would be to ask your local immigration office what they expect for the TM30. Very few people live on boats here.
To prevent trolls, I'm closing comments.
@Tamsin ******
, if you can find out what your local immigration office requires for a TM30 for people who live on boats, I'll reopen comments and let you post that information.
Thank you