It's possible to get a bank account without a long stay Visa but not easy. The Visa you could get to make it easier is a Non-O (retirement) but you have to be 50+.
I am on many of these groups and have yet to see a first hand post of someone using an onward ticket who had it refused. I have seen second hand reports such as yours so I am doing just what you say, waiting and watching.
If you don't have a Thai bank account get your Non-O before you travel as it will make getting one much easier and you'll not have to show proof of onward travel. If you do have a Thai bank account it's up to you to do what you find most convenient.
If it is your Visa expiring in November not your current entry stamp you can border bounce again before it expires to get a new 90 day stamp then plan for your 12 month extension