On Skyscanner there’s an option when you book with American Airlines that you book a flight without paying for it straight away. If you cancel your booking within 24 hours you don’t have to pay any fees. My advice would be to use this option just prior to your flight into Thailand and once you’ve gone through customs at the airport immediately cancel the booking. This is explained under the header ‘American Airlines cancellation policy’ on the following website with a direct link for booking one of those flights:
