How do I renew my retirement visa in Thailand and what considerations should I have for mental or physical disabilities?

6 months as tourists, of course.

I'd recommend you to look up recent experiences w/ METV. Yes, the METV has that 60 days and folks will remind you can extend it as well to get 90. The embassy will also happily hand it out as long as you pay and match the requirements. But they'll also mention that it is up to the immigration officer to decide if you are allowed into the country.

Which brings a gray area and a potential challenge with actually using that 60 days or even more in a long stay. Upon re-entry into the country you might be seenas someone who wants to (temporarily) live in Thailand. But with the METV being a tourist visa, you don't have a visa that allows this. Hence the immigration officer might ask you to proof you are a tourist doing tourist travel, activities, and you don't "live in the country".

Remember ,you need a flight out of the country before the end of you FIRST 60 days

Airbnb with issue you a TM30 to show where you are staying

With an METV you can come and go as you please during the 6 month period it is valid. Each entry, you will be stamped for 60 days which can be extended another 30. So if you max out (three 90 day stays), you likely need 3 flights in and 3 flights out - what you actually do once you have the 60 day or 30 day extension is up to you.

Note: Entering on the last day of valid METV still give you 60+30. If you intend to do 30 day extensions, submit a letter stating as such - I have done this with the SETV and as I have done it often, include a copy of the extension stamp from previous trip. You may have to create pdf files of all your flights and this letter as I haven't seen a way to upload more than one item per required topic (may exist for METV).

You will need to show more than one flight when applying for a MTV

Book/show your itinerary into Thailand and another ticket out to somewhere else within the first 60 days and then another ticket back to Thailand sometime after that.

To apply for an METV, you are formally required to document your travel plans, including at least two entries into Thailand and two onward journeys. How strictly this is enforced varies between embassies and consulates. Some require proof of two entries and two exits, while others issue an METV based on a single entry ticket. The best approach is to contact the embassy or consulate where you intend to apply and confirm their specific requirements.

If you apply without the required supporting documentation, you may either be issued a single-entry tourist visa without a refund of the price difference or be asked to upload additional documents before your application is processed.

Your airline might want to see a return ticket or an onward booking after 60 days. Accommodation you just mention the first hotel in the application.