Is proof of onward travel required within the duration of a Thai Tourist Visa?

Yes, when you enter Thailand on a Tourist Visa, the immigration authorities typically expect you to have proof of onward travel (such as a flight ticket) within the duration of your stay. With a standard Tourist Visa, you are allowed 60 days, which can be extended for an additional 30 days, resulting in a total of 90 days. Therefore, you should have an onward flight booked within that 90-day period.