OP, as usual it depends on your immigration office.
For your FIRST non O using "conversion" from visa exempt or tourist visa, it's common for immigration office to accept a TM30 as it's understandable to at this early stage you have not chosen long term rental.
Suggest you ask your immigration office for definitive advice.
Here is link with requirements for 12 months extension.
It does list rental agreement.
You can do a mok one as suggested earlier.
https://www.immigration.go.th/wp-content/uploads/2022/02/9.FOR-RETIREMENT-PURPOSES-50-YEARS-OLD-NON-O.pdf