You really need to talk directly to the embassy that will be doing your STV.
The official rules are it must be prepaid for the 90 days, including with a lease agreement. Embassies will vary what they will allow and not allow. Extention is probably easier.
I did the STV before the new stv restart at the first of the year. The embassy in Taipei first rejected my serviced apartment because it was not prepaid only authorized. I prepaid it and they accepted it. I did later cancel it, lease a condo, and was able to extend stv with lease agreement only (no prepayment).
As always, results may vary, from office to office, person to person, day to day.
a peice of advice, once you get the ticket from agency... Take the flight confirmation number and enter that into the airlines website and print from there rather than just using the agency confirmation page.
Some will hold the confirmation longer if needed, like apply for visa... If not most auto cancel in 3 days.
wow.. That semi surprising... They did chabge the testing requirements on me and only purchased a few days out. What *+%~>* Singapore airlines is. Seems silly to to make a flight requiring digital certificates from a country that does not issue them.
I would see if you could get a refund and fly someone else since your flight is so far out in the future.
Reach out to the embassy and explain. You only need to worry accommodation in the 90 day blocks, not all upfront.
I know people who were able to extend staying at a partners house. They used a letter and partners contact and had their partner available.
I do not recall anyone getting through the embassy though like this, but you can try. As always rules can vary office to office, person to person, day to day.
Others have also used a lease agreement created by a family member. That may or may not work, depending on the documentation. If they are the house owner, then better.
It's unlikely the the Nov 1 rules will be approved and published with full details until the last moment, probably about oct 28th.
It's extremely likely that if you enter Oct 28th, the new rules will not apply to you but will need to finish the sandbox as you started. This has been the way with all the changes.
I am a former STVer. Regarding your accommodation, it only needs booked 90 days for initial.. Then each renewal for that 90 days. They generally want it prepaid, but on renewal I just a lease agreement.
The STV is not convient if you want to move around thailand a lot. It was really made for staying in the same spot.
I just extended a visa exempt stamp today at MTT. Visa application with photo, copy of passport, copy of current stamp and tm6.. All signed of course. Passport with tm6 original. 1900 baht cash.
No other documents requested or offered (but had of course).