Keep/put as little capital in Thailand as possible. Invest your capital in your home country and transfer what you need (visa requirements, expenses) from the earnings. Rent, don't buy. Real estate is not an investment for foreigners in Thailand.
My non-o was approved and sent 2 days after I entered on 60day exempt. I took a couple of weeks to find housing,, then did border run to activate the non-o. Then jumped through the hoops to get bank account, vehicles and drivers licenses. Was easy. I used a border run company here in hua Hin to bounce in Myanmar.
And do note that you can't touch that 800k for 3 months after extension and it can never fall below 400k after that. 800k must be back 2 months before next extension.