Tod Daniels I might add ( certainly in the Uk ) once you have got the medical cert , police check and bank statement etc ) you need to go to a solicitor and get them bundled and notored .
As I say if you have a day or two spare , pop down there , on the left a team of people will tell you exactly what you need , and they will also copy and bundle every together for you , for a couple of hundred baht ..
it’s official so there’s no issue . It’s to help immigration . As they are so busy it saves getting refused by getting turned away on a minor detail
it’s on the list as a requirement and you need to obtain as near to the date of your visit as possible , ie a day before , so I always pre warn ( Bangkok bank ) go in they produce it showing balance etc on headed paper .. no problem .. this is ofcourse if you going the 800k route . Which in your case is irrelevant if you going by income as you say .
In my case at Jomtien in October.... bank book showing balance of 800k been in for 3 months , condo contract . Certificate from BKK bank . Passport , fee . In fact as you go into immigration. Look left and there’s ‘ official ‘ helpers to get everything sorted for you , tip 100 or 200 bht , they sort it all 👍🏼