I’m not an immigration expert, but I would think that if you don’t get the visa approved before your flight in the 12th, you could get a standard 60 day visa on arrival, then after you get the approval of the non-O visa, fly down to KL for a long weekend or a quick trip to Laos, then re-enter Thailand with your non-O visa. Can’t see why this would not work.
that’s odd. I’ve flown from Toronto to Bangkok loads of times, and most of those times, I didn’t have a return flight booked. Not once has Air Canada asked for proof of departure. Two years ago, I didn’t even have a Thai visa, but no problem.