From what I read on different posts it will depend where you apply, and even that is blurry. Some say Vientiane ask for 6 months but some post about recently transferred money and it’s fine, others say 3 months
6 months with all that money sitting is a little excessive but maybe ask your bank for a letter ? Maybe that will help
I’d I were you and if you are still eligible for the Non O visa you should keep it as it seems it give you more advantages on the long run compared to the DTV
DTV you have 6months+ extension 6months then go out and come back the other one give you a year (right?)