Your best bet would be to have the 3 proofs and evidence that you are going to the Myanmar embassy then leaving again. Bear in mind though that there seems to have been a spike in denials of entry recently
Meaning no disrespect but i think that's poor advice. A 30-day visa exempt can be extended for 30 more days, arrangements can be made for the airline, and, as I said, the Embassy in Paris is a pain in the ass
If I were you I would book a cancellable onward flight, print it out and show them that. The Thai embassy in Paris has to be the least user-friendly in Europe