the financials 'starting' out are minimal.. it is when you go to open your Thai bank account within the first 30 days of your 90 day 'O' Non Immigrant visa, the financials will become more apparent. ie. 800,000 thb in the Thai account for a full 2 months before applying for the 12 month extension.
A little bit of research will reveal everything required. Not as scary as you make it out to be.
I would advise the 'O' retirement Visa (if you over 50). You should adhere to the financial requirements (unless you go to an Agent) and make sure you come back to Thai just before the 'expiry' date of your current retirement visa so you can extend it again for another 12 months. Sounds like you should get the single entry retirement extension (1,900thb), and pay 1,000 for a 're-entry' permit when you go back to USA.
If it is Hua Hin main Immigration.. next day is perfectly OK... I have been going the 'next' day for the past 4 years.. but please feel free to do it all on the same day :)
You can go to Kasikorn on the Wednesday.. get your bank statements and bankbook updated before you go Immigration the next day (Thursday). I have always gone the day after Bank updates to Immigration.. not a problem. ps. I am in Hua Hin.
An option is to stay at a cheap Hotel for 1 night (in Nonthaburi) where they will submit the TM30.. you then ask for a copy of that TM30 and go back to your Nonthaburi Immigration. Should be no need to go back to Bangkok.
you sound like a cheap charlie (or charline)... the DTV encourages low-lifes to enter Thai for possibly 5 years.... do your 'cooking' class in the States!