What is the proof of funds requirement for a 45-day visa exemption at Chiang Khong border?

To obtain a 45-day visa exemption upon entering Thailand from Laos at Chiang Khong, you are generally expected to provide proof of funds. While the requirement is often quoted as 20,000 baht in cash per person, many travelers have noted that border officers do not always ask for this proof. It is advisable to have such funds available, preferably in small denominations. Some commenters also suggested that a bank document showing a non-detailed balance for the last three months could suffice, but cash might be the preferred method of proving funds.