"Hello Graham. About the two Non Os. So each one of them is for 90 days. Do I need proof of funds when applying (at an embassy outside of Thailand)? Are you sure I can apply twice a year for a retirement Non O? I currently am on a marriage Non O that will expire, no funds at all at the moment."
Yes, Embassies approving eVisa applications have their financial requirements for Non-O retirement applications which equates roughly to 800k banked or 65k per month income in the local currency in any accessible bank account in your name. (400k and 40k for marriage). See their website for details.
Two Non-Os from RTE London 6 months apart is exactly what I have been doing since before covid (except for the lockdown).
I got my residence certificate in 25 minutes and my DL in 75 minutes (Sa Kaeo province) - 100% legal as I did every test and total cost 310B. So you don't have an IDP?
With entries in March and September the timing for the application and approval has to be very precise. Two separate Non-O's is much simpler and probably cheaper.
Get a residence certificate from Immigration and a medical certificate from a doctor/clinic and, in case it is required, do the 1 hour online video test then turn up at the DLT with these plus copies of your passport, entry stamp and visa plus current driving licence and IDP to do the 3 simple reaction tests to get your licence. That was the process in Sa Kaeo (no video test required thou but some require it).