I have used onward tickets many times. They are valid for 48 hours but the airline do not check as they just want to see the booking. I have used a completely fake ticket as well.
I hope you chose 'long term living expenses in Thailand' with Wise otherwise it will not show as coming from abroad. You used to be able to do a combo with funds for retirement. Some in the bank and some monthly
I'm in the same boat as you. My Thai wife decided I didn't need a motorcycle licence when I renewed my car licence. I only rent bikes when I'm on an island holiday so now I'm not fully covered 😡
Just go and try different branches. It may be easier being away from tourist areas. The main stumbling block is proving where you live. Some banks will accept a sponsor so try your wife's bank first plus other banks will open an account if you buy their expensive insurance. Current money laundering laws have made it much harder to open a bank account. Good luck
there is no specific requirement but your re-entry is at the discretion of the IO so best not to just turnaround, unless you are with a visa agent group.