you said "she stays in the country for 3 months, most people know this as a visa." . . . . I am not "most people". I am a Thai visa expert. This is WRONG. These three months are a stay permit, they are not a visa
the DTV is a tourist visa, and you can't get a bank account opened on a tourist visa. As you are supposed to earn your money as a digital nomad with customers from abroad, Thailand expects you to withdraw the costs for a living in Thailand with your foreign credit card on a Thai ATM
: there is a single entry 60-days tourist visa, upon entering you get stamped in for a 60-days stay permit. This stay permit can get extended for 30 more days. The tourist visa becomes invalid upon entry. If you arrive without a visa, you do a visa-exempt entry and also get stamped in for a 60-days stay permit, which you can extend for 30 more days on Immigration for 1900 THB
your landlord is supposed to register your arrival in the accommodation. Some landlords do not follow suit. Then the responsibility is upon you. The fine for not registering or late registering is 2000 Baht
if you really "own" a property in Hua Hin, then you should have a blue housebook for it. With the blue housebook number, you can register "your property" in the TM30 online system. You will be issued a Log-in ID and a password, and you will be able to register every arrival using the TM30 by yourself
I got a SCB bank account since 20 years, and I must say, I am very satisfied with their onlinebanking App and their service every other year issuing the bank letter for Immigration. And the savings account earn a 1.2% interest, which pays the yearly Debit Card fee and earns me around 2600 THB on my 800,000+ THB