I understand. I've hung out with a few successful people and learned to delegate or outsource tasks to others when possible. I save that time for myself to do strategic thinking for my business or for education, and the rewards far out size the cost. And those costs are so much lower in Thailand it makes it even more doable.
I gathered the necessary documentation while I was in the US, brought it all to Thailand, and obtained my retirement Visa after I arrived here. I didn't do anything before arrival. Seemed to work fine in my case.
I can only speak for my personal experience and when I did my retirement Visa I was REQUIRED to have a Thai bank to satisfy the financial requirements. If you have a way of getting around this then that's great but I was not able to.