When you enter Thailand in international airports more than a few times and immigration has no mood, they can any questions, and anything they want accordingly with entry to Thailand and visa. If they ask you to show it, you just show the same documents that you submitted for Thai Embassy when you applied for DTV, or just open your own bank app and show your bank balance there ) Everyone who got DTV must have any bank account, so it's not big deal to follow up immigration officer requests.
DTV Soft Power Visa for medical treatment plan for 2 years too long to be trusted because ussuly it's takes much shorter time for dental treatment
- indicated that currently unemployed and have no income.
Additional context: long visa history
- "Please prove your monthly income. In case you are unemployed, please explain how you will sustain your life in Thailand": I attached a PDF explaining that I have over $60,000 in savings and experience in poker
Poker playing it's bad idea for official prove your monthly income
Anonymous participant possibly you have answered to your question. In case if you will come to immigration for visa extension possibly it will effect somehow, but if you never visit immigration office maybe nobody cares. It's looks like similar to situation when student study in Phuket School, but actually full time living and renting an apartment in Bangkok and never had a single chance to attend to class room for study. I have no idea what would happen with visa of this person in such situation.
Technically you can enter Thailand under 60 days stamp and it would not effect granting DTV. After granting DTV you will have to leave Thailand and re-enter with new DTV visa. Possible you will be not effected at all if lucky enough.
But generally it's still will be breaking rules. And if immigration officers will pay attention very well after during reentry or extensions it would be visible by dates that you were in Thailand when DTV was granted everyone would be able to see it by visa stamps. Generally it's not a big problem but can raise questions every time from immigration officers.
Anyway I would not recommend it to do to anyone. But if you have no choice under emergency situation...