I am not from the USA, but lots of American friends use their "maiden" name as a middle name, perhaps see if you can include that in the bank account name. During Covid my wife who travels into Thailand on her Thai Passport, couldnt get permission to enter as her vaccination certificates were in my surname, so eventually she got in using her Aussie passport, but our American friend just got hand witten vaccination certificates and they filled in whatever name they liked. the problem is the Thai Public service is very strict, and given the current levels of enforcement, I suggest the easiest way is to get matching documents, My wife finished up changing her Thai passport to her Married name, along with her ID card and her Bank accounts, Perhaps rather than use an agent, do you know any "Influential" Thai persons. If so get all your documents together and take them with you and see the Branch manager. If that person can certify, you are the one and same, they may accept them as a guarentor
Unless you have unique talent or profession, employment is impossible, you can be a millionaire if you start with 3 million in your country, the ladies will help you spend it. Thailand makes it very hard for potential migrants. You can buy an elite visa but you will still have to contribute taxes. You will not be able to buy land until you become a Thai citizen, even after qualifying to apply it can take at least 4 years, and you need to speak Thai as well. You can get married, and I wish you well, there are ladies waiting at the airport now, however by the time its ok to get a marriage visa. They may have spent all your money and have headed back to the Airport to wait for their next husband. In Short your chances are slim. Or you can pay an agent and take your chances.
Thinking forward, get a Thai passport and ID card, even though he doesn't need it now, it could be a lifesaver in years to come if he chooses to travel or work in ASIA
Probably easier for your wife to enter on her Canadian passport as they seem to assume all Thai women are there to work illegal. We have been there several times, Thai passport holders go through a separate lane, and they always give my wife a hard time. On her Aussie passport she walks straight through with me.
Why not just deposit the funds onto your Aust credit card, and buy it with the card (Assuming you are getting it from a dealer), I did that to pay a hospital bill. (I rang the bank and told them before hand)
When I commute from BKK to Hua Hin I use several options, the train, they have just upgraded the line and cut and hour of the trip. Major hotels in Hua Hin/bkk have buses running between and it s relatively easy to catch a ride, and their are other commercial bus companies as well. Driving/traffic is such a pain it's worth looking at the alternatives
My concerns would be if you move your residence and the Sh*t hits the fan sometimes in the future,and you need to return in a hurry for whatever reason the last thing you need is a bureaucrat tell you no you can't enter, your not a resident!!