@Scott ********************
, if you can enter Thailand for 30 days on visa-exempt and if airline let you chack-in and board without proper visa AND with outbound tickets later than 30 days are different things. If you have onward ticket within 30 days from arrival date, wouldn't be a problem to fly to Thailand. Other than that, you need to check with your airline clearly.
Unfortunately, airline policy is out of the scope of this group.