you can carry any currency. Just has to be equal to 20,000 baht. I keep 1000 usd just in case. But 20 ish times through on visa exempt, never once been asked
I've never been searched. Live in Thailand. I would just bring 12 months worth in your carry on. Or of youre feeling paranoid, use the old prison wallet.
I tried to do the income based one, and not keep money in the bank, I dont like banks. But they asked for information and stuff I could not provide. Like a work contract, a W2, letter from employer, over 80k a month in to my account was not enough for me