Sounds like your only short time in the countrys you visit, then no need to choose DTV, several other options with lesser requirements, if only being short time in Thailand.
DTV is a touristvisa, and therefor not eligible for a bankaccount ever.
And since their work is done outside Thailand, they will get their pay outside Thailand, and thereby a Thailand bankaccount is not needed.
To be eligble for a bankaccount, a real longterm visa is needed.
Banks in Thailand are like everywhere in the world, interested in having good stable custormers, that have a permanent address, a steady easy traceable income, and use the account all year round.
That is why the banks are reluctant to give accounts to people on short time ( read: tourist ) visas, and who only spend part of the year in Thailand.
Don’t expect to get a residence certificat, until you have stayed at a permanent adress in at least 3 month, since that is what the residence certificat should confirm.
Furthermore the added attention on whitewashing of money, is an added burden on the banks, so even depositing large amounts isn’t a guaranteed way to open an account.
The value of a resident certificat, had gone down, since Immigration Officers are giving them to people that are not on a longterm visa, or have stayed severel months at 1 adress in Thailand, so even if it is a formal requirement, the bank make up their own assesment of the stability of the want-to-be customer.