I have no idea what you are talking about. My specific example was in Jomtien and I got an extension today based on income. I am not married and I can do it with 65K. If someone cannot deposit and spend 65K every month, they would be in trouble living here.
Again, if you have the the 12 X 65+, you can get an extension based on income . Since you would have been here for, immigration " could" ask for proof of last year's requirements. For me they did not. Just make sure you have a bank letter like my example. My initial one got rejected because they put February on the letter and not March. Had to redo it.
I mentioned that a recent TM30 was needed. If you don't have one you need to get one, possibly by the things you mentioned. However, you would already have been around for a while and would already have one.
Again people are conflating income or bank. When someone shows up for an income extension it would mean they have probably been in in Thailand for at least a year and you would have 800 / 400 ฿ in the bank. So it is very plausible for immigration to ask for proof if that. I never had ฿800 in the bank for more than a few minutes, hence I was concerned.
if you have at least ฿65 K in your home bank just transfer to a Thai bank every month. No one has ever asked me if it comes from retirement, just that it is a foreign transfer.
for income method, 800K 400K only comes into play in that you need a visa for depositing the first 12 deposits. You start for the first 15 months and get your 12 deposits then switch. Do not try to think about the total just that you have at least 65K X 12