a year I PP. You should have save like $2000 per month unless living lavishly. In one year should have had $2400. We lived(2 people) for $1200 per month. I like the siem reap idea for you. Give you time to build more savings and maybe the exchange rate improves. Then do the 800 baht in bank route. Or get a agent now. Many do.
Vietnam is an option too for awhile to build funds just need to bounce every 3 months
I think you need more than a letter from yourself. I think proof of portfolio, tax return or company registration certificate within your country. I read in previous post no brokerage accounts