I live here and I am married to a Thai. I got married when I was here on a visa exemption. If you are over 50 I would recommend getting the Retirement visa rather than the Marriage, aside from the higher bank balance requirement, everything is much much simpler for the Retirement visa.
Getting a bank account is a spin of the wheel of luck. I gave up and used an “agent”, cost me 1000baht.
Your biggest hurdle is getting the permission to marry certificate. That is going to be your main priority.
I have a pdf of my passport on my phone which I always use to check in to hotels, I don’t like carrying my passport. I have only been refused at check in once, they insisted I have my passport.