Simple, go through an agence, it's their job. A simple google search will give you à few names

Like Brandon Thurkettle mentionned, if your embassy does not provide thai immigration with a letter certifying your income , for the first year you will either have to deposit 800k thb in your Thaï bank account or go through an agent. If you transfer more than 65k thb/month (every month, not 195k thb every 3 month) after the first year, you could get à letter from your bank confirming that and use it instead of 800k bht for the second year.

I depends, how much your time is worth?

Why do you assume that by doing a border run your visa would be renewed for an additionnal year?

I don't care what the visa you request say about insurance, don't you think that having a medical insurance is a good idea anyway? I would simply make sure that my police meets at least Thaï requirements

IF Thaï immigration says it needs to be stamped by Thaï embassy, get à lawyer to have it done for you.

Another work around but I don't know if it will work, get married again in Thaïland

The requirement to get a re5tiree visa in Thaïland is having 800 000B. It can be in one lump sur or being able to prove 65 000B/ month or a mix of both equaling 800 000B. The catch is that money has to be in a Thaï bank account so even ic yoh get 100 000B/month, you cannot prove it the first year.

Another option that is borderline illegal is to use an agent that will loan you the money ... for a fee

@Robert ********

the way I look at it is they did you à favor by showing you their true colors. They forgot that you did them à favor by using them. Your business will be better appreciated somewhere else

You're a Thaï tax resident if you stay in Thaïland more than 180 days during the year, not consecutly, total. Bank account has no bearing whatsoever on your residency. Without à bank account , you could fly under the radar more easily but you also forgo the conveniency of having à Thaï bank account. And if you get on their radar, they'll get you anyway. Remember, Al Capone was not cought by the FBI, he was cought by the IRS