I don’t think ‘you’ need to worry about this. Only proof of where you are staying. Copied this …. You do not need to submit a TM30 for yourself. Instead, this must be completed within 24 hours of your arrival by the owners of the lodging where you are staying. A fine of 800THB, increasing to 1600THB/person for the property owner, can be imposed for failure to accomplish this.
Depends on where you are from. I am British. Visited Phu Quoc in January and mainland last week. No visa required. If you are American you will require as they want to check you are not trying to invade 😂
it must surely be a yearly retirement visa? Not 90 days. (You do check in every 90 days) Your initial post says you have a multi entry. Do not let your retirement visa run out or you have to start again. Also if it’s not a multi entry, you must get a re-entry visa before you leave.
I have never heard of that visa. Are you sure it’s not a multi entry tourist visa? As already stated, you will not have any problem leaving on the day it expires. No harm in visiting immigration for advice several days before.