You'll need your funds for the visa in a personal account checking or savings only - nothing of an investment style. You'll want to do the soft power route Muay Thai or cooking classes as your not a digital nomad. Fight EVO360 Thailand - Thepprasit Boxing Stadium is familiar with the dtv, sends all documents same day. Good luck.
I asked at the border when I activated my DTV, as mine says clearly on it - not allowed to work. She said the original ones didn't specify if it was soft power or working visa. Now they adapted it.
Best to apply for DTV from your home country. If it's not approved when you get here that's ok, you can use it on a border bounce return. Fight EVO360 Thailand - Thepprasit Boxing Stadium does great for the muay Thai option, all forms sent same day and reasonable. Very knowledgeable on DTV visa.
I did Muay Thai with Fight EVO360 Thailand - Thepprasit Boxing Stadium and put unemployed with no trouble. If anything this is why they ask for tax returns. So as long as you have your money in a checking or savings account(no stocks or bonds accounts) and can show you paid your taxes then you should be fine.
Fight EVO360 Thailand - Thepprasit Boxing Stadium is gym in pattaya with all the proper paperwork and knowledge of the visa, make sure you get a gym like this to make everything easy - not all of them are as prepared.