when you leave the country just get a new departure card from the immigration counter at the airport. fill it out and cue up again. i personally did this and friends of mine too. absolutely 0 problem.
go to the bank, have them print-out a confirmation of what you need for one year and stamp them. they will understand when you say for visa/immigration/one year. i think i paid about 300 baht and i had a confirmation that in a period of time my account was always over 800k.
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