Someone posted earlier their extension experience and it differed to yours but offices differ in the treatment of extensions. Good for you having an easy extension.
You will be fine, I have done 4 reentries, no problem, never asked to show anything. Vast majority of DTVERS have no issues. You also need to complete a TDAC before arrival.
I think you will need to double check with Taipei if they accept a fixed deposit with immediate access. When I applied there, they were very particular on funds in a personal bank account and being able to see where the 500K comes from. Maybe easier to top up your bank account to get to the 500K THB. Your PayPal account is acceptable to demonstrate income deposits, using it for evidencing the 500K is where it can be unacceptable. Remember to submit your Jigyou touroku shoumeisho - business registration certificate.