Is my plan for a Non-O retired visa in Thailand after returning home at the end of October feasible?

I am doing exactly the same as you. Came over in February on non o. Went to bank and asked what I needed to open account. Do this close to where you plan to stay.Went to local immigration office and asked for their list of requirements. For the driving license Bring your national and international driving license with you. You need medical. This can be done local clinic on most main streets cost 100-200 ฿. I had to do the full motor cycle test and converted the car license.

I'm now back in Thailand the deposit has seasoned over 2 months. Went to local immigration yesterday to check landlord has registered my tm30. Which they had. I brought all the paperwork with me and they looked through it. Said I need to call back mid next week when I have less than 45 days left on visa. A few things to do in bank before. Letters confirming funds , 3 month bank statement. And on the day I call to immigration to get extension I have to update my bank pass book. I felt doing it in two stages was better for me.

Another consideration for me was that I am generally in Thailand June to September so I'll be here in July to the extension in July next year.

I think your original plan is the best option. It should help you get all the bank and driving license sorted out, so when you’re back in November, you can enjoy your time here without having to worry about them.

As my plan always was just to hibernate for 6 months, I timed my trip carefully, with an eye onto the best dates. I entered Thailand on an October 3rd, on a 90-days Non-Imm-O Retirement Visa, I got stamped in for 90 days until January 4th. Then I applied for the 1-year Extension of stay on December 21. I not only got issued an EOS starting on January 5 every year since 17 years (!!), this day of my annual application always done between December 16 and 24 also always is the day I can do my 90-days report! Usually my hibernation is from Sepetember 26 thru March 20. . . . . . . . On Immigration, I get everything done on the same day: my 90-days report, the new 1-year extension for 1900 Baht, and a single re-entry permit for 1000 Baht. All of it within 20-30 minutes. Immigration Sisaket. The advantage: I only make one 90-days report, which is combined with the application to the extension. I only need one trip to Immigration. I do the TM30 online by myself (house of my GF is registered in the TM30 system)

The timing is a bit tight but you might be able to get your 12 month extension of stay before you leave in October then get a reentry permit so you can go back home and return. Your other option would be make your 1st trip on a visa exempt entry, go home in October and apply for the Non-O visa and come back in November and open your bank account etc. Option C would be get back to back Non-O visas like you originally posted.

Why not just do the one year extension before you leave? Just be sure to get an exit/entry permit before you leave at the end of October. That would be the easiest option in my opinion instead of applying for another visa.